1. A genus of herbaceous plants with leaves of three lentlets, such as clover; an ornament of three cusps in a circle, resembling three-leaved clover.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• refil,
• trevail,
• treail,
• refail,
• treffic,
• refoll,
• trumoil,
• trefic,
• arofoil,
• trefrog,
• trefool,
• trefoill,
• trafoil,
• trefoyl,
• treneil,
• kiefkil,
• qutrefoil,
• trefel,
• traphol,
• treful

• trifle,
• trifler,
• true bill,
• triavil,
• true-false,
• trifolium,
• truffle,
• trafalgar,
• trifling,
• travail.

The adjective form of the word "trefoil" is "trefoiled".

The plural of the "trefoil" can be the "trefoils".

The singular of the "trefoil" can be the "trefoil".