Слэнг

Slang is a kind of language consisting of very informal words and phrases. Slang is more common in speech than in writing. Slang words are often used in a particular context or by a particular group of people. These are English slang words beginning with the letter A.
ace (1) - very skillful, very good at something

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

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"

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

app - a computer software application

armpit - a very unpleasant place

arty, artsy - displaying an interest in the arts or high culture
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

Offensive slang

These words should be used with care. Although they are not particularly "hot", they can be offensive to the person they are applied to. For example, if you call somebody an "airhead", that person could be insulted although anybody listening would not be shocked.
airhead - a silly, stupid person
alky, alkie, alchy - an alcoholic
ankle-biter - a child