O.E. ofer-cuman "to reach, overtake," also "to conquer, prevail over," from ofer "over" + cuman "to come" (see
come). A common Gmc. compound (cf. M.Du. overkomen, O.H.G. ubarqueman, Ger. überkommen). In ref. to mental or chemical force, "to overwhelm, render helpless,"