careless (adj.)

Old English carleas "free from anxiety; unconcerned," from care (n.) + -less; a compound probably from Proto-Germanic (compare Old Norse kærulauss "quit, free"). Original senses extinct by mid-17c. (now in care-free); main modern meaning "not paying attention, inattentive, not taking due care" is attested by 1560s (in carelessly). Meaning "done or said without care, unconsidered" is from 1650s.