- abnormal: Deviating from the normal or average
- abstain: to hold oneself back voluntarily
- acrobat: a skilled performer of gymnastic feats, as walking on a tightrope or swinging on a trapeze or a person who readily changes viewpoints or opinions
- acronym: a word formed from the initial letters or groups of letters of words in a set phrase or series of words
- Acrophobia: a pathological fear of heights
- Aigosthena: the citadel or high fortified area of an ancient Greek city
- alter: an elevated place or structure, as a mound or platform, at which religious rites are performed or on which sacrifices are offered to gods, ancestors, etc
- altitude: extent or distance upward; height
- Ambidextrous: able to use both hands equally well
- ambivalence: uncertainty or fluctuation, esp. when caused by inability to make a choice or by a simultaneous desire to say or do two opposite or conflicting things
- Ambivert: one whose personality type is intermediate between extrovert and introvert
- anarchy: having no ruler
- anesthesia: loss of sensation with or without loss of consciousness
- anonymous: not named or identified
- antonym: a word opposite in meaning to another
- apathy: lack of feeling or emotion
- atheist: one who denies the existence of god
- aversion: an instinctive contrariety or opposition in feeling
- avert: To turn away or aside in avoidance
- somethingmeter: a sensitive aneroid barometer that is graduated and calibrated, used chiefly in aircraft for finding distance above sea level, terrain, or some other reference point by a comparison of air pressures or any device used for the same purpose that operates by some other means, as by radio waves.