Synonyms

definitely

American

[def-uh-nit-lee] / ˈdɛf ə nɪt li /

adverb

in a clear and definite manner; unambiguously.
unequivocally; positively.

Synonyms:

certainly, absolutely

interjection

(used to express complete agreement or strong affirmation).

Are you starting your diet tomorrow? Definitely!

definitely British

/ ˈdɛfɪnɪtlɪ /

adverb

in a definite manner
(sentence modifier) certainly

he said he was coming, definitely

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

unquestionably: used to confirm an assumption by a questioner

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Usage

What does definitely mean? Definitely is an adverb that usually means certainly or without a doubt. It also has this meaning when it’s used as a single-word response.Definitely is also sometimes used as an adverb to describe an action as clearly defined or precise. When definitely is used as a single word in response to a question or other statement, it is called an interjection or sentence substitute. When used this way, it is very similar to saying certainly or absolutely.Example: I will definitely be there tomorrow—I promise.

Related Words

See clearly.

Etymology

Origin of definitely

First recorded in 1575–85; definite + -ly

Compare meaning

How does definitely compare to similar and commonly confused words? Explore the most common comparisons:

definitely vs. defiantly

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

He is definitely a breed of footballer that the Premier League has needed.

From BBC • Apr. 3, 2026

“We definitely didn’t see this coming,” she said.

From The Wall Street Journal • Apr. 1, 2026

“From Micron’s perspective, they definitely see signs that suggest this time is indeed different. AI and the data center are driving the current inflection, making memory more of a strategic asset.”

From MarketWatch • Apr. 1, 2026

So it definitely became real when he gave us the address of where he was at.”

From Los Angeles Times • Mar. 31, 2026

An hour or more of that and her instrument definitely would have been damaged.

From "Clairboyance" by Kristiana Kahakauwila

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023