Shamrocks for St. Patrick's Day! Secret Meaning: Lightness The name shamrock comes from Irish seamróg, which is the diminutive of the Irish word for clover (seamair) and means simply "little clover" or "young clover". Shamrock usually refers to either the species Trifolium dubium (lesser clover, Irish: seamair bhuí) or Trifolium repens (white clover, Irish: seamair bhán). Saint Patrick, Ireland's patron saint, is said to have used the shamrock's three leaves as an illustrative metaphor for the Christian Holy Trinity.