| antedate | Precede in time; come before (something) in date | |
| antediluvian | Of or belonging to the time before the biblical Flood | |
| antipode | A direct or exact opposite | |
| apace | Swiftly, quickly, at a fast pace | |
| apartheid | A policy or system of segregation or discrimination on grounds of race | |
| aplomb | Self-confidence or assurance, especially when in a demanding situation | |
| apocryphal | A story or statement of doubtful authenticity, although widely circulated as being true | |
| apoplectic | Overcome with anger; extremely indignant | |
| apostle | A vigorous and pioneering advocate or supporter of a particular policy, idea, or cause | |
| apothegm | A concise saying or maxim; an aphorism | |