Old English carleasnes "freedom from anxiety;" see careless + -ness. Original sense obsolete. Modern meaning "heedlessness, negligence" (1560s) probably is a fresh formation.
careful
carefully
carefulness
caregiver
careless
carelessness
cares
caress
caret
caretaker
care-worm
)window.location='https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=byronic106@yahoo.com&lc=US&item_name=Donation+to +Help+Keep+Etymonline+Free+and+Open&no_note=0&cn=&curency_code=USD&bn=PP-DonationsBF:btn_donateCC_LG.gif:NonHosted'){kind=link}