| Term | Definition |
| Abase | v. lower; degrade; humiliate |
| Abash | v. embarrass |
| *Abate | v. subside or moderate |
| Abbreviate | v. shorten |
| Abdicate | v. renounce; give up |
| *Aberrant | adj. abnormal or deviant |
| Aberration | n. deviation from the expected or the normal |
| Abet | v. assist, usually in doing something wrong |
| *Abeyance | n. suspended action |
| Abhor | v. detest; hate |
| Abject | adj. wretched; lacking pride |
| Abjure | v. renounce upon oath |
| Ablution | n. washing |
| Abnegation | n. renunciation; self sacrifice |
| Abolish | v. cancel; put an end to |
| Abominable | adj. detestable; extremely unpleasant |
| Abominate | v. loathe; hate |
| Aboriginal | adj. being the first of its kind in a region; primitive; native |
| Abortive | adj. unsuccessful; fruitless |
| Abrasive | adj. rubbing away; tending to grind down |
| Abridge | v. condense or shorten |
| Abrogate | v. abolish |
| Abscission | n. cutting off; separation |
| *Abscond | v. depart secretly and hide |
| Absolute | adj. complete; totally unlimited; certain |
| Absolve | v. pardon (an offense) |
| Abstain | v. refrain; withhold from participation |
| *Abstemious | adj. sparing in eating and drinking |
| Abstinence | n. restraint from eating or drinking |
| Abstract | adj. theoretical; not concrete; nonrepresentational |
| Abstruse | adj. obscure; profound; difficult to understand |
| Abusive | adj. coarsely insulting; physically harmful |
| Abut | v. border upon; adjoin |
| Abysmal | adj. bottomless |
| Abyss | n. enormous chasm; vast, bottomless pit |
| Academic | adj. relating to school; not practical or directly useful |
| Accede | v. agree |
| Accelerate | v. move faster |
| Accessible | adj. easy to approach |
| Accessory | n./adj. additional object; useful but not essential thing |
| Acclaim | v. applaud; announce with great approval |
| Acclimate | v. adjust to climate or environment |
| Acclivity | n. sharp upslope of a hill |
| Accolade | n. award or merit |
| Accommodate | v. oblige or help someone; adjust or bring into harmony; adapt |
| Accomplice | n. partner in crime |
| Accord | n. agreement |
| Accost | v. approach and speak first to a person |
| Acerbity | n. bitterness of speech and temper |
| Acetic | adj. vinegary |
| Acidulous | adj. slightly sour; sharp; caustic |
| Acknowledge | v. recognize; admit |
| Acme | n. peak; pinnacle; highest point |
| Acoustics | v. science of sound; quality that makes a room easy or hard to hear in |
| Acquiesce | v. assent; agree passively |
| Acquittal | n. deliverance from a charge |
| Acrid | adj. sharp; bitterly pungent |
| Acrimonious | adj. bitter in words or manner |
| Acrophobia | n. fear of heights |
| Actuarial | adj. calculating; pertaining to insurance statistics |
| Actuate | v. motivate |
| Acuity | n. sharpness |
| Acumen | n. mental keenness |
| Acute | adj. quickly perceptive; keen; brief and severe |
| Adage | n. wise saying; proverb |
| Adamant | adj. hard; inflexible |
| Adapt | v. alter; modify |
| Addendum | n. addition; appendix to a book |
| Addiction | n. compulsive; habitual need |
| Addle | v. muddle; drive crazy; become rotten |
| Address | v. direct a speech to; deal with or discuss |
| Adept | adj. expert at |
| Adhere | v. stick fast |
| Adherent | n. supporter; follower |
| Adjacent | adj. adjoining; neighboring; close by |
| Adjunct | n. something added on or attached |
| Adjuration | n. solemn urging |
| Adjutant | n. staff officer assisting the commander; assistant |
| *Admonish | v. warn, reprove |
| Adorn | v. decorate |
| Adroit | adj. skillful |