backside

noun

back·​side ˈbak-ˌsīd 

1

informal

a

: the part of the body that a person sits on : buttocks

I slid down on my backside, heaving or rowing myself with my arms and using my good leg for steering …

—Oliver Sacks

b

: the part of the body of a four-legged animal corresponding to the buttocks : rump sense 1a

… admits she hit the dog's backside but denies hitting it on the head.

—Ann Krueger

2

or back side : the side or surface opposite the front or face of something : the farthest or reverse side : back

A tight, rocky couloir drops down the backside of the peak …

—Mike Beaudry

The guy with the clipboard pulled me over, pointed to an innocuous little knob on the back side of the engine and said it's part of the computer and needs to be replaced.

—Tom and Ray Magliozzi

3

or back side

a

: the side opposite the homestretch on a racecourse : backstretch

When challenged on the backside the final time around, Tudor Palm would have no part of it, and burst to the lead again.

—Jackie Burke

b

: the part of a playing field or court (as in football or basketball) that is away from where the main action or play is occurring

—often used before another noun

a backside tackle

c

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

The duo had a little trouble on the backside, though, as they bogeyed the par-3 11th hole.

—Brian Girasoli

Synonyms

• behind
• booty [slang]
• bootie
• bottom
• breech
• bum
• buns
• butt
• buttocks
• caboose
• can
• cheeks
• derriere
• derrière
• duff
• fanny
• fundament
• hams
• haunches
• heinie [slang]
• hunkers
• keister [slang]
• keester
• nates
• posterior
• rear
• rear end
• rump
• seat
• tail
• tail end
• tush [slang]

Examples of backside in a Sentence

our backsides were sore after sitting on those hard benches for so long

Recent Examples on the Web

Though this may not seem like a big deal, those backside receiver blocks could be the difference between an explosive run or a home run. —Ted Nguyen, New York Times, 13 May 2025

Because back nine is close to backside, and backside is just far too colloquial. —Paulina Dedaj, FOXNews.com, 8 Apr. 2025

Two additional paddles are also easily accessible on the machine’s backside. —PC Magazine, 31 Mar. 2025

Instead of storms, the region is getting wind on the backside of these weather systems. —Brayden Garcia, Fort Worth Star-Telegram, 20 Mar. 2025

Word History

First Known Use

14th century, in the meaning defined at sense 2

Rhymes for backside

• abide
• allied
• applied
• aside
• astride
• azide
• bankside
• bastide
• bayside
• bedside
• belied
• beside

Kids Definition

backside

noun

back·​side ˈbak-ˈsīd 

informal

: buttock sense 2a

Medical Definition

backside

noun

back·​side -ˌsīd 

: buttocks

—often used in plural