Meaning of A in English

A

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.