| Trefoil 1. (n.) Any plant of the genus Trifolium, which includes the white clover, red clover, etc.; -- less properly, applied also to the nonesuch, or black medic. See Medic. 2. (n.) An ornamental foliation consisting of three divisions, or foils. 3. (n.) A charge representing the clover leaf. Thesaurus Entries clover, deuce-ace, leash, set of three, shamrock, tercet, ternary, ternion, terzetto, three, threesome, tierce, trey, triad, trialogue, triangle, tricorn, trident, triennium, trihedron, trilogy, trimester, trine, trinity, trinomial, trio, triphthong, triple crown, triple threat, triplet, triplopy, tripod, triptych, trireme, triseme, triskelion, trisul, triumvirate, triunity, trivet, troika |