ABC

1 ABC /ˌeɪˌbiˈsiː/ noun
plural ABCs or ABC's
1 ABC
/ˌeɪˌbiˈsiː/
noun
plural ABCs or ABC's
Britannica Dictionary definition of ABC
1 
: the letters of the English alphabet
[plural]
[singular]
2 
: the most basic or important information about a subject
[plural]
[singular]

(as) easy as ABC

— see 1easy
2 ABC abbreviation
2 ABC
abbreviation
Britannica Dictionary definition of ABC
1 
American Broadcasting Corporation
◊ ABC is one of the major television networks in the U.S.
2 
Australian Broadcasting Corporation