English slang words and phrases beginning with the letter “A”. 

Abo 
an Australian Aborigine, Aboriginal, koori

abortion
a total failure

abs
abdominal or stomach muscles

ace (1)
very skillful, very good at something

ace (2)
to easily pass an exam or a test

acid
the potent hallucinogenic drug lysergic acid diethylamide, or LSD

action (1)
important or exciting activity

action (2)
sexual activity

admin
administrator, administration, person or department that runs an organisation

afters 
dessert, sweet dish eaten after the main course of a meal

aggro 
aggressive, violent

ain’t
slang contraction of “is not”, “are not”, “am not”, “have not” and “has not”

airhead 
a silly, stupid person

airy-fairy
overly idealistic, lacking down-to-earth common sense

alky; alkie; alchy 
an alcoholic

ammo
ammunition

ankle-biter 
a child

antsy 
restless, impatient, unsettled

ape; apeshit
(in phrases go ape and go apeshit) wild excitement or great anger

app
a computer software application

armpit
a very unpleasant place

arse; ass (1) 
backside, bottom, buttocks

arse; ass (2) 
a stupid person, a stubborn fool

arse-licking 
saying nice things to someone in order to get something from them

arsehole; asshole 
a selfish, unpleasant, obnoxious person

arty; artsy
displaying an interest in the arts or high culture

ass-kisser 
someone who says nice things to someone in order to get something from them

Aussie 
Australian, Australia

awesome
amazing, impressive, really cool

axe; ax (1)
to dismiss someone from a job (v.); dismissal from a job (n.)

axe; ax (2)
a musical instrument, esp. a jazz musician’s guitar, trumpet or saxophone