Trefoil (disambiguation)

A trefoil (three leaf) is a graphic form composed of three leaves or lobes.

Trefoil may also refer to:
 * Clover, or trefoil, common names for plants of the genus Trifolium
 * Trefoil Island, an island in Australia, part of Tasmania’s Trefoil Island Group
 * Trefoil, Alberta, a locality in Special Area No. 2, Alberta, Canada
 * Trefoil knot, the simplest example of a nontrivial knot
 * Trefoil, a variation of the card game La Belle Lucie
 * Trefoils, a variety of Girl Scout cookie
 * Trefoil-class concrete barge, an American Type B ship
 * USS Trefoil (IX-149)
 * USS Trefoil (1865), a Union Navy steamer