Abate
To cease, subside, reduce
Abash
To shame and embarrass
Abdicate
To give up a position or power
Abiding
Continuing or lasting
Abortive
Not able to be completed
Abscond
To secretly run away and hide
Absolve
To be free from sin/blame
Abstain
To voluntarily hold back or not participate
Abstruse
Difficult
Abysmal
Utterly hopeless
Accost
To approach boldly
Acquiesce
To give in or surrender
Acrid
Harsh, Sharp, Offensive
Acrophobia
Intense fear of heights
Acumen
Sharp insight, keenness of mind
Acute
Sharp, pointed
Adherent
Follower, disciple
Adjudicate
To settle a case on court
Admonish
To reprimand and scorn
Adroit
Adept (under pressuring conditions)