certain

Etymology

From Middle English certeyn, certein, certain, borrowed from Old French certain, from a Vulgar Latin unattested form *certānus, extended form of Latin certus (“fixed, resolved, certain”), of the same origin as cretus, past participle of cernere (“to separate, perceive, decide”). Displaced native Middle English wis, iwis (“certain, sure”) (from Old English ġewiss (“certain, sure”)) and alternative Middle English spelling sertane (“some, certain”).

adj

1. Sure in one's mind, positive; absolutely confident in the truth of something.
   I was certain of my decision.
2. Not to be doubted or denied; established as a fact.
   Now that more experiments have been run, the theory is certain and the argument is settled.
3. Sure to happen, inevitable; assured.
   It is certain that Spain will reach the finals. / Spain is now certain to reach the finals. / Spain is now certain of a place in the finals.
   Bankruptcy is the certain outcome of your constant gambling and lending.
4. Unfailing; infallible.
   I have often wished, that I knew so certain a remedy in any other disease 1702, Richard Mead, Mechanical Account of Poisons
5. Fixed; regular; determinate.
   at certain intervals
6. Particular and definite, but unspecified or unnamed; used to introduce someone or something without going into further detail.
   Every wine has a certain distinctive character which sets it apart from all others.
   Each morning, she would see a certain man rush past her window on his way to work.
7. (preceded by "a", of a person) Named but not previously mentioned.
   Looking inside the cover, they learned that the book had once belonged to a certain R. Jones.
8. (obsolete) Determined; resolved.

det

1. Having been determined but not specified.
   Certain people are good at running.

pron

1. (with of) Unnamed or undescribed members (of).
   She mentioned a series of contracts, of which certain are not cited.