What does certainly mean?
"Certainly" is an adverb used to express strong conviction or emphatic agreement — it signals that something is true beyond reasonable doubt. It appears most often before verbs and adjectives to intensify a statement ("He is certainly talented") or after auxiliary verbs ("She has certainly worked hard"). It also functions as a polite, somewhat formal one-word reply granting permission or confirming agreement: "Certainly, come right in." The word conveys confidence and assurance, and in negative constructions it reinforces denial ("I certainly never said that"). Derived from the Latin certus, meaning fixed or settled, via Old French certain, it entered English in the medieval period alongside related words such as certainty and ascertain. Its versatility across everyday speech, writing, and polite conversation makes it one of the most useful adverbs for expressing conviction in English.
adverbUsed to emphasize that a statement is true or that the speaker agrees with it; without doubt. Also used as a polite affirmative reply.
- Emphatically affirming the truth or likelihood of something; without doubt.
- As a polite, formal way of agreeing to a request or granting permission: 'Certainly.'
"She will certainly be remembered for her generosity."
"The results will certainly influence future policy decisions."
""May I borrow your pen?" "Certainly.""
Every time you say 'certainly,' you're echoing the Latin certus — 'fixed, settled, resolved' — the same root that gives us 'certificate,' a document that makes things officially settled.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of certainly
"Certainly" derives from the Latin certus, meaning fixed, settled, or determined, which passed into Old French as certain before entering Middle English. The adverb was formed from the adjective "certain" with the native English suffix -ly, appearing in English by around the early 14th century. It shares its Latin root with words such as certainty, ascertain, certificate, and concert.
How certainly is actually used
Fully standard in both British and American English and neutral in register, though as a standalone reply ('Certainly.') it carries a slightly more formal or courteous tone than a simple 'sure.' In negative contexts it often strengthens a denial: 'I certainly didn't mean to offend you.'
Easily confused with certainly
There is no standard English word 'curtainly'; the similar-sounding 'curtain' is a noun for a hanging fabric, while 'certainly' is an adverb of certainty.