c.1300, "to trip or miss one's footing" (physically or morally), probably from a Scandinavian source (cf. dialectal Norwegian stumla, Swedish stambla "to stumble"), probably from a variant of the Proto-Germanic base *stam-, source of Old English stamerian "to stammer," German stumm "dumb, silent." Possibly influenced in form by stumpen "to stumble," but the -b- may be purely euphonious. Meaning "to come (upon) by chance" is attested from 1550s. Stumbling-block first recorded 1526, used in Rom. xiv:13 to translate Greek skandalon.
