| acumen | The ability to make good judgments and quick decisions, typically in a particular domain | |
| acrimonious | Angry and bitter in tone or manner | |
| acquisitive | Eager to acquire and possess things especially material possessions or ideas | |
| acme | The point at which someone or something is best, perfect, or most successful | |
| acerbic | sharp and forthright, especially of a comment or style of speaking | |
| accumulate | To gather or collect, often in gradual degrees; heap up | |
| accretion | The process of growth or increase, typically by the gradual accumulation of additional layers or matter | |
| accolade | An award or privilege granted as a special honor or as an acknowledgment of merit | |
| accede | To agree or express agreement | |
| abysmal | Extremely bad; appalling | |