the.com/reckless
the absence of a reck, which nobody has reckoned with in 700 years
means Acting without care or thought for the consequences, heedless of danger.
from From Old English 'reccelēas,' built on 'recan/reccan,' a verb meaning 'to care or heed' — so 'reckless' literally means 'careless' in the oldest sense. That root 'reck' was once a perfectly healthy word ('it recks me not'), and is likely related to German 'geruhen' (to deign) and other Germanic words for caring or minding. Over the centuries 'reck' withered away on its own, leaving 'reckless' as a near-orphan — a negative whose positive has all but vanished from the language.
lost wordreck meant care; we kept only its absence
old englishreccan, to take heed, died out alone
orphan termreckless survives but reckful went extinct
legal weightrecklessness sits between intent and accident in court
speed linkreckless driving is a charge in every US state