1
a : the 1st letter of the English alphabet
b : a graphic representation of this letter
c : a speech counterpart of orthographic a
2
: the sixth tone of a C-major scale
3
: a graphic device for reproducing the letter a
4
: one designated a especially as the first in order or class
5
a : a grade rating a student’s work as superior in quality
b : one graded or rated with an A
6
: something shaped like the letter A
7
capitalized : the one of the four ABO blood groups characterized by the presence of antigens designated by the letter A and by the presence of antibodies against the antigens present in the B blood group.