אוֹת ʼôwth (H226)

a signal (literally or figuratively), as aflag, beacon, monument, omen, prodigy, evidence, etc.

1) sign, signal 1a) a distinguishing mark 1b) banner 1c) remembrance 1d) miraculous sign 1e) omen 1f) warning 2) token, ensign, standard, miracle, proof

probably from אוּת (H225) (in the sense of appearing);