Certus

Part of speech: adjective

Definitions

1. Having a firm conviction or being assured of truth or reliability; certain to occur or definite in outcome; acting with confidence based on knowledge or evidence
2. Exhibiting a guaranteed assurance or sureness about something; bound to happen without doubt or uncertainty; displaying confidence derived from established facts or proof
3. Marked by absolute surety or conviction; inevitably destined or unquestionably fixed in nature; proceeding with unwavering confidence grounded in certainty

Etymology: Latin "certus" began as a word about sorting, not sureness. It is the past participle of "cernere," which meant to sift or separate, as grain is sifted from chaff. From the physical act came the sense of distinguishing one thing from another, and then of deciding. A "certus" thing was one that had been separated out and settled, its identity fixed. That history explains why the adjective covers both a fixed fact and a confident mind. Latin speakers used it of a settled plan, a definite amount, or a matter beyond dispute, and confidence grew from the idea of something already determined. English "certain" descends from it through French, keeping the sense of something settled beyond question.

Synonyms: certain, sure, definite

Antonyms: uncertain, unsure, doubtful