tre ‧ foil /ˈtriːfɔɪl, ˈtrefɔɪl/ BrE AmE noun [countable] technical
[ Date: 1300-1400 ; Language: Old French ; Origin: trefeuil , from Latin trifolium , from tri- 'three' + folium 'leaf' ]
1 . a type of small plant that has leaves which divide into three parts
2 . a pattern in the shape of these leaves