trefoil/ˈtɹɛ.fɔɪl/EtymologyFrom Middle English trefoil, from Old French trifoil, trefeul, from Latin trifolium, from tri- (“three”) + folium (“leaf”).trefoil means any of several plants of the pea family, having compound, trifoliate leaves; especially one of the genus Trifolium. Lexicurio rates it Rare gem — a strength score of 81 out of 100.nounAny of several plants of the pea family, having compound, trifoliate leaves; especially one of the genus Trifolium.A symbol having the shape of such leaves, especially when used as an architectural ornament.“"The pristine, unbroken condition of the vessel – sometimes called a trefoil jug – caused the entire dig to 'come to a halt,' Søvsø remarked."”