Meaning of ABC in English

ABC

(~s)

1.

The ~ of a subject or activity is the parts of it that you have to learn first because they are the most important and basic.

...the ~ of Marxism.

N-SING: N of n

2.

Children who have learned their ~ or their ~s have learned to recognize, write, or say the alphabet. (INFORMAL)

N-COUNT: poss N

Collins COBUILD.      Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) .