c. 1600 (transitive), from French submerger (14c.) or directly from Latin submergere "to plunge under, sink, overwhelm," from sub "under" (see sub-) + mergere "to plunge, immerse" (see merge). Intransitive meaning "sink under water, sink out of sight" is from 1650s, made common 20c. in connection with submarines. Related: Submerged; submerging.