The Collaborative International Dictionary of English v.0.48:
Sea purse \Sea" purse`\ (s[=e]" p[^u]rs`). (Zool.) The horny egg case of a skate, and of certain sharks. [1913 Webster]WordNet (r) 3.0 (2006):
sea purse n 1: the seaward undercurrent created after waves have broken on the shore [syn: undertow, sea puss, sea-puss, sea purse, sea-purse, sea-poose]