guarded (adj.)

mid-15c., from guard (n.) or from Old French garder "to keep watch over, guard, protect, maintain, preserve" (corresponding to Old North French warder, see gu-), from Frankish *wardon, from Proto-Germanic *wardon "to guard" (from PIE root *wer- (3) "perceive, watch out for"). Italian guardare, Spanish guardar also are from Germanic. Related: Guarded; guarding.

1590s, "not furnished with a guard," from un- (1) "not" + guarded. Sense of "not on one's guard, not taking heed" is attested from 1630s.