means A deadlock in which opposing sides hold their positions and neither will back down or make the first move.

from A plain English compound — 'stand' plus 'off,' meaning to stand apart or keep one's distance. 'Stand off' worked as a verb (to hold aloof, to keep away) long before it hardened into the single noun 'standoff,' which carries the sense of two forces standing apart, locked and unmoving. 'Stand' descends from Old English 'standan,' a deep Germanic root for staying upright and unmoved; 'off' is simply 'of,' an old marker of separation. The word's flavor of a tense, frozen confrontation is largely an American development.