As a boy's name this is a pet form of Jeremy or Gerald, or occasionally of Gerard and Jerome. As a girl's name it is a variant spelling of Gerry, and is sometimes bestowed as an independent given name, as in the case of the American model and actress Jerry Hall (b. 1956).
English, Welsh, and Irish: from the personal name Piers, the usual Norman vernacular form of Peter. In Wales this represents a patronymic ap Piers. In Ireland it represents a reduced Anglicized form of Gaelic Mac Piarais ‘son of Piaras’, a Gaelicized form of Piers.