Tre"foil (?), n. [L. tres three + E. foil leaf; cf. F. frefle, 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.
2. Arch.
An ornamental foliation consisting of three divisions, or foils.
3. Her.
A charge representing the clover leaf.
© Webster 1913.