Learn how to say Trefoils correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word trefoil:
a small European plant of the pea family, with yellow flowers and three-lobed clover-like leaves.
Genera Trifolium and Lotus, family Leguminosae: several species, in particular the bird’s-foot trefoil
a plant with three-lobed leaves that is similar or related to the trefoil.
an ornamental design of three rounded lobes like a clover leaf, used typically in architectural tracery:
a thing having three parts; a set of three:
a trefoil of parachutes lowers the shuttle’s used rockets to Earth
Middle English: from Anglo-Norman French trifoil, from Latin trifolium, from tri- ‘three’ + folium ‘leaf’