Careless
来自Big Physics
Old English carlēas ‘free from care’ (see care, -less).
wiktionary
From Middle English careles, from Old English carlēas(“careless, reckless, void of care, free from care, free”), equivalent to care + -less. Cognate with Icelandic kærulaus(“careless, negligent”).
etymonline
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.