The Collaborative International Dictionary of English v.0.48:
Sea god \Sea" god`\ A marine deity; a fabulous being supposed to live in, or have dominion over, the sea, or some particular sea or part of the sea, as Neptune. [1913 Webster]WordNet (r) 3.0 (2006):
sea god n 1: a deity that personifies the sea and is usually believed to live in or to control the sea