Synonyms of certain

certain

adjective

ˈsər-tᵊn 

1

as in one

known but not named

a certain person told me that today is your birthday

Synonyms & Similar Words

• one
• some
• unnamed
• unspecified
• anonymous
• specific
• unidentified
• given
• particular

Antonyms & Near Antonyms

• known
• named
• specified

2

as in sure

having or showing a mind free from doubt

I'm certain that they'll arrive on time

Synonyms & Similar Words

• sure
• confident
• positive
• assured
• doubtless
• implicit
• clear
• sanguine
• cocksure
• resolute
• decisive
• self-assured
• self-confident
• unwavering
• unquestioning
• unfaltering
• unhesitating
• self-conceited

Antonyms & Near Antonyms

• uncertain
• doubtful
• unsure
• dubious
• hesitant
• indecisive
• unassuming
• wavering
• vacillating
• diffident

3

as in stable

having been established and usually not subject to change

a certain percentage of the profits will go to charity

Synonyms & Similar Words

• stable
• final
• fixed
• unchanging
• unchangeable
• determinate
• set
• hard
• specific
• frozen
• firm
• settled
• flat
• hard-and-fast
• constant
• steady
• definite
• uniform
• inexpugnable
• explicit
• exact
• good
• sure
• given
• true
• stipulated
• reliable
• stated
• responsible
• safe
• dependable
• nonnegotiable
• solid
• noncancelable
• nonadjustable
• unwavering
• trustworthy
• tried
• trusty
• tried-and-true

Antonyms & Near Antonyms

• adjustable
• negotiable
• changeable
• unspecified
• indefinite
• uncertain
• variable
• volatile
• unpredictable
• fluid
• unstable
• capricious
• fluctuating
• mercurial
• temperamental
• mutable
• unsettled
• inconstant
• unsteady
• open-ended
• changeful
• flickery

4

as in necessary

impossible to avoid or evade

as he got older, the athlete began to feel the certain effects of the aging process on his body

Synonyms & Similar Words

• necessary
• inevitable
• possible
• definite
• unavoidable
• sure
• inescapable
• probable
• ineluctable
• destined
• unescapable
• in the cards
• likely
• in the bag
• decided
• ineludible
• relentless
• settled
• predetermined
• fated
• inexorable
• preordained
• predestined
• unremitting
• unstoppable
• foreordained

Antonyms & Near Antonyms

• uncertain
• unsure
• doubtful
• avoidable
• questionable
• unclear
• dubious
• preventable
• unlikely
• shaky
• evadable
• undecided
• unreliable
• unsettled
• improbable
• undependable

5

as in reliable

not likely to fail

chicken soup is grandma's certain cure for pretty much whatever ails you

Synonyms & Similar Words

• reliable
• sure
• surefire
• infallible
• unfailing
• deadly
• dependable
• can't-miss
• fail-safe
• unerring

Antonyms & Near Antonyms

• uncertain
• doubtful
• questionable
• fallible

6

as in definite

not capable of being challenged or proved wrong

up to this point there's been no certain evidence that a crime has been committed

Synonyms & Similar Words

• definite
• positive
• sure
• conclusive
• unquestionable
• undeniable
• indubitable
• indisputable
• incontestable
• irrefutable
• incontrovertible
• unanswerable
• unarguable
• irrefragable
• accomplished
• unchallengeable
• inarguable
• absolute
• unambiguous
• unequivocal
• clear
• decisive
• undisputed
• unquestioned
• uncontested
• uncontradicted
• hands-down

Antonyms & Near Antonyms

• problematic
• questionable
• arguable
• debatable
• controversial
• negotiable
• uncertain
• disputable
• answerable
• moot
• disputed
• doubtful
• dubious
• ambiguous
• controvertible
• inconclusive
• theoretical
• refutable
• doubtable
• contradictable
• academic
• indecisive
• hypothetical
• speculative
• debated
• iffy
• equivocal

Synonym Chooser

How does the adjective certain contrast with its synonyms?

Some common synonyms of certain are cocksure, positive, and sure. While all these words mean "having no doubt or uncertainty," certain may apply to a basing of a conclusion or conviction on definite grounds or indubitable evidence.

police are certain about the cause of the fire

When would cocksure be a good substitute for certain?

In some situations, the words cocksure and certain are roughly equivalent. However, cocksure implies presumptuous or careless positiveness.

you're always so cocksure about everything

When is it sensible to use positive instead of certain?

While the synonyms positive and certain are close in meaning, positive intensifies sureness or certainty and may imply opinionated conviction or forceful expression of it.

I'm positive that's the person I saw

When could sure be used to replace certain?

The words sure and certain are synonyms, but do differ in nuance. Specifically, sure usually stresses the subjective or intuitive feeling of assurance.

felt sure that I had forgotten something

Example Sentences

Recent Examples of certain

However, Miami-Dade Tax Collector Dariel Fernandez said the state is allowing a limited transition period for certain applicants. —Ivan Taylor, CBS News, 7 Feb. 2026

If guys aren’t going to hold themselves to certain competitive standards, Gobert suggested, Wolves coach Chris Finch should start benching the culprits. —Jace Frederick, Twin Cities, 7 Feb. 2026

In order to operate in Portland, certain businesses must be approved for conditional use and are subject, pursuant to Portland’s zoning provisions, to restrictions outlined in their respective conditional use permits. —Mia Cathell, The Washington Examiner, 7 Feb. 2026

The atmosphere is believed to be lethally toxic, though this is not known for certain. —Richard Edwards, Space.com, 7 Feb. 2026

Phrases Containing certain

• for certain
• of a certain age