The Collaborative International Dictionary of English v.0.48:
Sea tang \Sea" tang`\ (Bot.) A kind of seaweed; tang; tangle. [1913 Webster] To their nests of sedge and sea tang. --Longfellow. [1913 Webster]WordNet (r) 3.0 (2006):
sea tang n 1: any of various coarse seaweeds [syn: tang, sea tang]