1. A plant of the genus Trifolium
   "Children often search for four-leaf trefoils for good luck";
   - clover
    
2. Any of several Old World herbs of the genus Medicago having small flowers and trifoliate compound leaves
   "trefoil plants are important forage crops for livestock";
   - medic, medick
    
3. An architectural ornament in the form of three arcs arranged in a circle
   "The Gothic cathedral featured intricate trefoil designs in its stained glass windows"

Derived forms: trefoils

Type of: architectural ornament, herb, herbaceous plant

Part of: genus Medicago, genus Trifolium, Medicago, Trifolium

Encyclopedia: Trefoil