proskomma

4348 proskomma (pros'-kom-mah);

from 4350; a stub, i.e. (figuratively) occasion of apostasy:

KJV-- offence, stumbling (-block, [-stone]).

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4350 proskopto (pros-kop'-to);

from 4314 and 2875; to strike at, i.e. surge against (as water); specifically, to stub on, i.e. trip up (literally or figuratively):

KJV-- beat upon, dash, stumble (at).

STUMBLING BLOCK

A cause of stumbling; anything that leads others to sin. The word is used literally as well as symbolically . Christ was a stumbling block to the unbelieving people of His own nation, just as He continues to be a stumbling block today to all those without faith in Him <1 Cor. 1:23>. Christians may also be stumbling blocks when they exercise their freedom at the expense of those who are weak <1 Cor. 8:9>. Also OFFENSE.

(from Nelson's Illustrated Bible Dictionary)