| abandon | Lack of constraint or inhibition |
| abate | To decrease in; to reduce |
| abet | To assist, to act as an accomplice |
| abjure | To renounce under oath; to abandon |
| abnegate | To deny; to give up |
| abortive | Ending without any specific results |
| abrogate | To abolish by authoritative means |
| abscond | To depart quickly in secret |
| abstemious | Done in moderation; consuming sparingly |
| accede | To authorize; to express permission or approval |
| acclivity | An ascending slope or incline |
| accretion | A growth in size or amount |
| acme | The highest level or degree possible |
| actuate | To activate; to put into motion; to influence to activity |
| acuity | Sharp vision or perception distinguished by the ability to see subtle details |
| acumen | Sharpness of insight, understanding, and mind; shrewd |
| adamant | Inflexible; unyielding |
| adept | Exceptionally skilled |
| adjudicate | To act as a judge; to settle an issue |
| adjure | To appeal to |
| admonish | To warn or caution; to advise |
| adroit | Accomplished; highly competent; very skilled |
| adulation | Excessive flattery or admiration, usually insincere |
| adumbrate | To give an indication or hint about events in the near future |
| aerie | A nest built very high in the air; an elevated, isolated dwelling |
| affected | Phony; artificial |
| aggregate | The total; the sum |
| algorithm | An established method for solving a problem/equation |
| alimentary | Relating to food, nutrition, or digestion |
| allay | To ease, lessen, decrease in intensity |
| amity | Friendship, good intention |
| amorphous | Lacking a definite form |
| animus | A feeling of ill will |
| anodyne | A source of comfort; a pain-relief medicine |
| anomaly | Something that is hard to classify; abnormal compared to the common |
| anthropomorphic | Giving human qualities or characteristics for inanimate objects or animals |
| antiquated | Too aged to be fashionable or useful in any way |
| aphorism | A statement of a principle |
| aplomb | Self-assurance; poise |
| apostate | One who renounces or defies a religious faith |
| apposite | Extremely well-adapted or appropriate |
| apprise | To notify; inform |
| appropriate | To assign for a particular job or purpose; allocate |
| arable | Fertile; suitable for agriculture |
| arcane | Little-known; secret; obscure; elusive |
| archipelago | A large chain or group of islands |
| arrears | Overdue or unpaid debts/bills; a forgotten, neglected promise |
| arrogate | To claim without any authorization or justification; without right |
| askance | With disapproval; with a such sideway's glance |
| assent | To agree, usually for a proposal |
| atavistic | A characteristic of a previous time or era; ancient, past |
| autocrat | A dictator |
| aver | To declare as true |
| avuncular | Regarded as the characteristics of an uncle; kind and warm |
| awry | Wrong; askew |