Old English socian (intransitive) "to soak, to lie in liquid," from Proto-Germanic *sukon (cognates: West Flemish soken), possibly from PIE *sug-, from root *seue- (2) "to take liquid" (see sup, v.2). Transitive sense "drench, permeate thoroughly" is from mid-14c.; that of "cause to lie in liquid" is from early 15c. Meaning "take up by absorption" is from 1550s. Slang meaning "to overcharge" first recorded 1895. Related: Soaked; soaking. As a noun, mid-15c., from the verb.