Wiktionary
n. A sheet tailored to form pocket for a mattress with elastic edges that is suitable for a range of mattress sizes. The edge may also contain a drawstring to secure the sheet more firmly and enable use on a wider range of mattress thickness.
WordNet
n. a sheet (usually with elastic edges) tailored to fit a particular mattress [syn: contour sheet]
Usage examples of "fitted sheet".
The bed was unmade, a discolored flat-sheet and an olive-drab Army blanket tangled on a yellowed fitted sheet.
It has no covers, just a dingy, rumpled white form-fitted sheet and a stained pillow that has lost its shape and is almost flat.
It was a concave rectangle-about four yards by two-like a huge fitted sheet .
Nadine nodded, barely visible under the folds of a slightly ragged fitted sheet.
The top left side of the fitted sheet had come undone from the mattress.
The center of the fitted sheet was stained, and a single strand of black curled-up hair lay in the stain.