An Etymological Dictionary of the German Language/Annotated/dick
dick, adjective, ‘thick, stout, corpulent,’ from Middle High German dic, dicke, adjective, ‘thick, dense, frequent,’ Old High German dicchi, ‘thick, dense’; in English too the double meaning of the adjective obtains; compare Old Icelandic þykkr, þjǫkkr, Anglo-Saxon þicce, English thick. Corresponds to Old Irish tiug (from *tigu), ‘thick,’ so that we must presuppose a Gothic *þiqus. Beside which the double sense, ‘thick, dense,’ makes the kinship with dicht probable. In Old High German the meaning ‘dense’ has been preserved in Dickicht, literally ‘a place densely overgrown’ (originally used by sportsmen); in Middle High German dicke is the equivalent term.