A-cup Definition

adjective
Sized so as to fit an A cup.
That A-cup bra might fit better.
Wiktionary
noun

A standard, relatively small, bra cup size, consisting of a measurement around the bust that is one inch longer than a measurement around the band, plus five inches.

Wiktionary
(by synecdoche) A woman whose breasts fit a A-cup bra.
Wiktionary
(by synecdoche) A woman with small breasts.
Wiktionary

Other Word Forms of A-cup

Noun

Singular:
a-cup
Plural:
a-cups