a

noun

1. first letter of the English alphabet
2. musical note
3. anything shaped like the latter A
4. sounds associated with the letter A

1. one; any indefinite example of

preposition

1. (to do with position or direction) in, on, at, by, towards, onto
2. (to do with separation) in, into
3. (to do with time) each, per, in, on, by

noun

1. musical note
2. letter in the Latin alphabet
3. human blood type