noun, plural A's or As, a's or as.
the first letter of the English alphabet, a vowel.
any spoken sound
represented by the letter A
as in bake, hat, father,
something having the shape of an A .
a written or printed representation of the letter A or a.
a device, as a printer's type, for reproducing the letter A or a.
from A to Z, from beginning to end; thoroughly; completely: He knows the Bible from A to Z.