back

1 of 4

noun

ˈbak 

plural backs

1

a(1)

: the rear part of the human body especially from the neck to the end of the spine

(2)

: the body considered as the wearer of clothes

They were left with nothing but the clothes on their backs.

(3)

: capacity for labor, effort, or endurance

Put your back into it!

(4)

: the back considered as the seat of one's awareness of duty or failings

get off my back

(5)

: the back considered as an area of vulnerability

the police officer's partner always watches his back

b

: the part of a lower animal (such as a quadruped) corresponding to the human back

riding on the back of an elephant

c

: spinal column

She had surgery on her back.

d

: spine sense 1c

The title is on the book's back.

2

a

: the side or surface opposite the front or face

I only saw him from the back.

: the rear part

the back of the head

the back of the mirror

also : the farther or reverse side

wrote the number on the back of an envelope

b

: something at or on the back for support

back of a chair

c

: a place away from the front

sat in back

3

: a position in some games (such as football or soccer) behind the front line of players

also : a player in this position

a defensive back

4

informal : a swimming race in which swimmers use the backstroke

She placed first in the 100-meter back.

backed

ˈbakt 

adjective

backless

ˈbak-ləs 

adjective

back

2 of 4

adverb

1

a

: to, toward, or at the rear

asked the crowd to move back

b

: in or into the past : backward in time

looking back on her youth

an event back in the last century

Back then, no one had ever heard of chronic fatigue syndrome.

also : ago

several years back

met him in the street two days back

c

: to or at an angle off the vertical

leaned back on his chair

d(1)

: under restraint

He wanted to fight but his friends held him back.

holding back a laugh

(2)

: in or into a delayed condition

Bad weather set the launch date back several days.

The meeting was pushed back at the last minute.

Season 2's final episodes were held back for a few weeks … before finally airing.

—Nick Valdez

e

: in an inferior or secondary position

especially : behind a competitor in points or ranking

finished three strokes back

2

a

: to, toward, or in a place from which a person or thing came

She left home and never went back.

put the book back

b

: to or toward a former state

went back to private life

c

: in return or reply

forgot to write back

back

3 of 4

adjective

1

a

: being at or in the back

back door

b

: distant from a central or main area

back roads

c

of a speech sound : articulated at or toward the back of the oral passage : formed deep within the mouth

back vowels

2

: having returned or been returned

3

: being in arrears : overdue

is owed several months in back pay

4

: moving or operating backward : reverse

back action with oars

5

: not current

back issues of a magazine

6

golf : constituting the final 9 holes of an 18-hole course

back

4 of 4

verb

backed; backing; backs

transitive verb

1

a

: to support by material or moral assistance

backing a candidate for governor

—often used with up

back up a friend in a fight

b

: substantiate

—often used with up

needs to back up her argument with evidence

c

: to assume financial responsibility for

back a new company

d

: to provide musical accompaniment for

—often used with up

a singer backed up by a guitarist

2

a

: to cause to go back (see back entry 2 sense 1a) or in reverse

back the car into the garage

b

: to articulate (a speech sound) with the tongue farther back : to form deeper within the mouth

3

a

: to furnish with a rear part : to furnish with a back (see back entry 1 sense 2)

back a skirt with stiff material

b

: to be at the rear part of : to be at the back (see back entry 1 sense 2) of

a row of garages back the building

intransitive verb

1

: to move backward

backed into a parking space

—often used with up

back up to give him some space

Let's back up a little to clarify what we're saying.

2

of the wind : to shift counterclockwise compare veer entry 1 sense 2

3

: to have the rear part facing in the direction of something

The house backs onto a golf course.

backer

ˈba-kər 

noun

Phrases

back of one's hand or back of the hand

: a show of contempt

back of one's mind

: the part of one's mind where thoughts and memories are stored to be drawn on

behind one's back

: without one's knowledge

talking about me behind my back

in back of

: behind

One day, I was sitting in the tiny parlor in back of the store …

—John McNulty

back and fill

1

nautical : to manage the sails of a ship so as to keep it clear of obstructions as it floats down with the current of a river or channel

2

: to take opposite positions alternately : shilly-shally

has been back and filling on the issue

back into

: to get into inadvertently

backed into the antiques business

Synonyms

Noun

• rear
• reverse
• tail

Adverb

• ago
• agone [archaic]
• since
• syne [chiefly Scottish]

Adjective

• aft
• after
• hind
• hinder
• hindmost
• posterior
• rear
• rearward

Verb

• advocate
• champion
• endorse
• indorse
• patronize
• plump (for)
• plunk (for)
• plonk (for)
• support

Choose the Right Synonym for back

support, uphold, advocate, back, champion mean to favor actively one that meets opposition.

support is least explicit about the nature of the assistance given.

supports waterfront development

uphold implies extended support given to something attacked.

upheld the legitimacy of the military action

advocate stresses urging or pleading.

advocated prison reform

back suggests supporting by lending assistance to one failing or falling.

refusing to back the call for sanctions

champion suggests publicly defending one unjustly attacked or too weak to advocate his or her own cause.

championed the rights of children

recede, retreat, retract, back mean to move backward.

recede implies a gradual withdrawing from a forward or high fixed point in time or space.

the flood waters gradually receded

retreat implies withdrawal from a point or position reached.

retreating soldiers

retract implies drawing back from an extended position.

a cat retracting its claws

back is used with up, down, out, or off to refer to any retrograde motion.

backed off on the throttle

Examples of back in a Sentence

Noun

She was carrying her little daughter on her back.

She has a pain in the small of her back.

I slapped him on his back to congratulate him.

She stabbed him in the back.

He had his hands behind his back.

a bird with a dark back

riding on the back of a horse

a comfortable chair with a padded back

Adverb

The soldiers moved back from the front lines.

The police asked the crowd to move back from the scene of the accident.

He left his friends two miles back.

She turned around and looked back toward him.

a chapter beginning several pages back

He left his home and never went back.

It's time to go back home.

She took the book off the shelf and forgot to put it back.

In the opening chapter the author looks back on his youth.

an event back in the last century

Adjective

He keeps his wallet in his back pocket.

We came in through the back entrance.

We drove on the back roads instead of the main roads.

The company owes him several months in back pay.

Verb

I'm backing him for President.

She backed the winner of the race and won a lot of money.

She backed her argument with written evidence.

She backed the singer on the guitar.

She backed into a parking space.

She backed out of the garage.

The dog kept growling but backed off cautiously.

back a skirt with stiff material

Recent Examples on the Web

Noun

My mattress feels like new as the panels holding it up keep the bed firm to support my back. —Audrey Lee, Architectural Digest, 12 May 2025

But for the time being, the eyes of new running backs coach Eric Bieniemy, Johnson and Poles are mostly on Monangai. —Phil Rogers, Forbes.com, 12 May 2025

Adverb

He was ordered to pay back $9,402,678 in restitution and serve 10 years on probation. —Jennifer Sangalang, USA Today, 13 May 2025

Just a few blocks from arrival, the car lurched toward the other lane—which was, thankfully, empty—and immediately jerked back. —Matteo Wong, The Atlantic, 13 May 2025

Adjective

One of the first Georgians to enroll in the program in 2023, Seaborn had written a letter thanking his insurance provider for covering a procedure for his back pain. —Margaret Coker, ProPublica, 14 May 2025

Nothing about them has changed, but since the back half of 2024, when two of the sport’s highest-profile players were sanctioned for breaching them, the anxiety players feel has intensified. —Charlie Eccleshare, New York Times, 14 May 2025

Verb

Longtime collaborators and two-time Palme d’Or winners Ken Loach and Paul Laverty have shared a lengthy open letter backing Put Your Soul On Your Hand And Walk, the latest feature from Iranian filmmaker Sepideh Farsi, which debuts this evening in Cannes. —Zac Ntim, Deadline, 15 May 2025

An investment fund backed by the United Arab Emirates, MGX, also used $2 billion in stablecoin issued by the Trump family’s World Liberty Financial to invest in Binance earlier this year. —Sara Dorn, Forbes.com, 15 May 2025

Word History

Etymology

Noun

Middle English, from Old English bæc; akin to Old High German bah back, Old Norse bak

Adverb

Middle English bac, aphetic form of abak aback

Adjective

Middle English, partly attributive use of bac, back back entry 1, partly derivative of back back entry 2

Verb

verbal derivative of back entry 1

First Known Use

Noun

before the 12th century, in the meaning defined at sense 1a(1)

Adverb

13th century, in the meaning defined at sense 1a

Adjective

15th century, in the meaning defined at sense 1a

Verb

1548, in the meaning defined at transitive sense 1a

Phrases Containing back

• a monkey on someone's back
• answer back
• answer (someone) back
• a pat on the back
• a slap on the back
• at/in the back of one's mind
• baby back ribs
• back and fill
• back and forth
• back arrow
• back away
• back bacon
• back burner
• back button
• back channel
• back-check
• back dive
• back down
• back east
• back end
• back-formation
• back home
• back in action
• back in business
• back in/into circulation
• back into
• back issues
• back is to/against the wall
• back judge
• back matter
• back mutation
• back nine
• back of
• back of beyond
• back off
• back-office
• back of house
• back-of-the-envelope
• back order
• back-ordered
• back out
• back/paint oneself into a corner
• back passage
• back pay
• back room
• back rub
• back-scratching
• back seat
• back side
• back talk
• back-to-back
• back to front
• back up
• beat back
• be back
• be (back) in the swing of things
• behind someone's back
• bite back
• blink back tears
• bounce back
• break the back of
• bring back
• bring back to life
• brought it all back
• brought/pulled back from the brink of
• (can) trace one's history (back) to
• carry (someone) back to
• check back
• check back with
• choke back
• circle back
• clap back
• claw back
• come back
• come back from
• come back from the dead
• come back to
• come back to bite one
• come back to haunt
• come back with
• cut back
• date back
• date back to
• double back
• draw back
• drop back
• fall back
• fall back on
• fall back upon
• fight back
• fight back tears
• fight back the tears
• flash back
• flat on one's back
• from way back
• front to back
• get back
• get back at (someone)
• get back to
• get back to work
• get/go back to nature
• get/go back to (the) basics
• get one's back up
• get one's life back together
• get one's own back
• get the monkey off one's back
• give back
• give (someone) the shirt off one's back
• go back
• go back a long way
• go back on
• go back on one's promise
• go back on one's word
• go back to
• go back to square one
• go back to the drawing board
• got back to sleep
• go way back
• hand back
• hang back
• hark back
• hark back to
• harken back
• have eyes in the back of one's head
• have (someone) back
• have someone's back
• have (something) back
• hearken back
• hit back
• hold back
• hold back one's tears
• hold back (someone or something )
• in back
• keep back
• keep (someone or something) back
• kick back
• knock back
• know something like the back of one's hand
• ladder-back
• laid-back
• lie back
• (like) water off a duck's back
• look back
• money-back
• money-back guarantee
• never looked back
• on/off one's back
• on the back burner
• on the back of
• pat on the back
• play back
• plow back
• push (something) to the back of one's mind
• put back
• put one's back into
• put one's life back together
• put someone's back up
• relate back to
• report back
• roach back
• roar (back) to life
• roll back
• running back
• scratch one's back
• scratch someone's back
• see the back of
• set back
• sit back
• slick back/down
• snap back
• snapper-back
• stab in the back
• stand back
• step back
• strike back
• swept-back
• take a back seat
• take back
• talk back
• the back of beyond
• there's no going back
• there's no holding him back
• the small of the/one's back
• the straw that breaks/broke the camel's back
• think back
• throttle back
• through the back door
• throw back
• to hell and back
• toss back
• turn back
• turn back the clock
• turn one's back
• turn one's back on
• walk back
• want (back) into
• watch one's back
• watch someone's back
• went behind his back
• write back
• You scratch my back, and I'll scratch yours

Rhymes for back

• ack
• brack
• clack
• crack
• dak
• flack
• flak
• hack
• jack
• knack
• lac
• lack

Video

When Body Parts Are Also Verbs

Head, shoulders, metaphors, and toes

Kids Definition

back

1 of 4 noun

ˈbak 

1

a

: the rear part of the human body especially from the neck to the end of the spine

b

: the corresponding part of a four-footed or lower animal

2

: the part of something that is opposite or away from the front part

3

: something at or on the back for support

back of a chair

4

a

: a position in some games (as football or soccer) behind the front line of players

b

: a player in this position

backed

ˈbakt 

adjective

backless

ˈbak-ləs 

adjective

back

2 of 4 adverb

1

a

: to, toward, or at the rear

b

: in or into the past : ago

c

: in or into a reclining position

d

: under control : in check

held back

2

: to, toward, or in a place from which a person or thing came

3

: in return or reply

write back

talk back

back

3 of 4 adjective

1

a

: being at or in the back

back door

b

: distant from a central or main area

back roads

2

: not yet paid : overdue

back rent

3

: no longer current

back issues of a magazine

back

4 of 4 verb

1

: to give aid or support to

2

: to move or cause to move back or backward

3

: to shift in a counterclockwise direction

the wind backed around

4

: to provide with a back

backer noun

Medical Definition

back

noun

ˈbak 

1

a

: the rear part of the human body especially from the neck to the end of the spine

b

: the corresponding part of a lower animal (as a quadruped)

c

: spinal column

2

: the part of the upper surface of the tongue behind the front and lying opposite the soft palate when the tongue is at rest

Legal Definition

back

adjective

1

: being overdue or in arrears

back rent

2

: being retroactive especially as compensation

reinstated with back pay

Geographical Definition

Back

geographical name

ˈbak 

river 605 miles (974 kilometers) long in Nunavut, Canada, rising along the border with the Northwest Territories and flowing east-northeast into the Arctic Ocean