Definitions for "Fat Quarter"
A 1/4 yard of fabric cut 18" x 22".
A piece of fabric that measures approximately 18 by 22 inches, rather than the 9 by 44 inches of a regular (aka long) quarter yard. Quilters like these because 1) it's possible to cut bigger pieces out of them and 2) they don't get as tangled up in the wash as long quarters.
a yard of fabric cut into quarters measuring approx