"trefoil" in the noun sense
1. medic, medick, trefoil
any of several Old World herbs of the genus Medicago having small flowers and trifoliate compound leaves
2. clover, trefoil
a plant of the genus Trifolium
3. trefoil
an architectural ornament in the form of three arcs arranged in a circle
Source: WordNet® (An amazing lexical database of English)
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