Meaning of A in English
I. A 1 BrE AmE , a /eɪ/ noun ( plural A’s , a’s )
1 . [uncountable and countable] the first letter of the English alphabet
2 . [uncountable and countable] the sixth note in the musical ↑ scale of C ↑ major or the musical ↑ key based on this note
3 . [countable] the highest mark that a student can get in an examination or for a piece of work:
I got an A in French.
Julia got straight A’s (=all A’s) in high school.
⇨ ↑ A level
4 . an A student American English someone who regularly gets the best marks possible for their work in school or college
5 . [uncountable] used to refer in a short way to one of two different things or people. You can call the second one B:
A demands £500, B offers £100.
⇨ plan A at ↑ plan 1 (5)
6 . from A to B from one place to another
get/go from A to B
Hiring a car was the best way to get from A to B.
7 . from A to Z describing, including, or knowing everything about a subject:
the history of art from A to Z
8 . A34, A40 etc the name of a road in Britain that is smaller than a ↑ motorway , but larger than a ↑ B-road ⇨ ↑ A-road
9 . [uncountable] a common type of blood
II. A 2 BrE AmE
the written abbreviation of amp or amps
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012