trefoil

n. [ L. tres three + E. foil leaf; cf. F. frèfle, It. trifoglio, L. trifolium. See Tri-, Foil leaf, and cf. Trifoly. ] 1. (Bot.) 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 Clover, and Medic. [ 1913 Webster ]

2. (Arch.) An ornamental foliation consisting of three divisions, or foils. [ 1913 Webster ]

3. (Her.) A charge representing the clover leaf. [ 1913 Webster ]