sham·rock / ˈshamˌräk/ • n. a low-growing, cloverlike plant (esp. Trifolium minus) of the pea family, with three-lobed leaves, used as the national emblem of Ireland. ∎  a spray or leaf of this plant.ORIGIN: late 16th cent.: from Irish seamróg ‘trefoil’ (diminutive of seamar ‘clover’).

shamrock the national emblem of Ireland, and traditionally said to have been employed by St Patrick to explain the nature of the Trinity. The shamrock of legend has been identified with a number of different related plants with three-lobed leaves.

The word is recorded in England from the late 16th century, and comes from Irish seamróg ‘trefoil’, diminutive of seamar ‘clover’.

shamrock Plant with three-part leaves, usually taken to be Trifolium repens or T. dubium, the national emblem of Ireland. Legend tells that St Patrick used it to symbolize the Trinity. Other plants called shamrock include Oxalis acetosella and Medicago lupulina. Family Fabiaceae/Leguminosae.

shamrock XVI. — Ir. seamrǒg, dim. of seamar clover.