| Term | Definition |
| appraise | to assess the worth or value of |
| apprehend | 1.to seize, arrest 2.to perceive, understand, grasp |
| approbation | praise |
| appropriate | to take, make use of |
| aquatic | relating to water |
| arable | suitable for growing crops |
| arbiter | one who can resolve a dispute, make a decision |
| arbitary | based on factors that appear random |
| arbitration | the process or act of resolving a dispute |
| arboreal | of or relating to trees |
| arcane | obscure, secret, known only by a few |
| archaic | of or relating to an earlier period in time, outdated |
| archetypal | the most representative or typical example of something |
| ardor | extreme vigor, energy, enthusiasm |
| arid | excessively dry |
| arrogate | to take without justification |
| artifact | a remaining piece from an extinct culture or place |
| artisan | a craftsman |
| ascertain | to perceive, learn |
| ascetic | practicing restraint as a means of self-discipline, usually religious |