Acidulous: Slightly sour, having a harsh tone or manner.
Acerbic: Tasting bitter, having a biting expression.
Accretion: Growth through a slow buildup.
Acclimate: To adapt to something, even a new environment.
Abstemious: Restrained in consumption, especially of food and drink.
Abscess: An area of inflamed and pus-filled tissue.
Abrogate: To formally eliminate or abolish something.
Abjure: To reject solemnly or by a formal process.
Abject: Being in an extremely miserable state.
Abhorrent: Extremely Disgusting Or Repugnant
Aberrant: Turning Away From Normal.
Abdicate: To Formally Give Up Power Or Position.
Abate: To Lessen, Reduce