- any of a number of plants with leaves divided into three leaflets, as the clover, tick trefoil, and certain species of lotus
- a flower or leaf with three lobes
- any ornamental figure resembling a threefold leaf
Origin of trefoilMiddle English treyfoyle from Anglo-French trifoil from Classical Latin trifolium, three-leaved plant from tri-, tri- + folium, a leaf: see foil
- Any of various plants of the pea family, chiefly of the genera Trifolium and Lotus, having compound trifoliolate leaves.
- An ornament, symbol, or architectural form having the appearance of a trifoliolate leaf.
Origin of trefoilMiddle English from Anglo-Norman trifoil from Latin trifolium tri- tri- folium leaf ; see bhel-3 in Indo-European roots.