means The unlawful, deliberate killing of one person by another, treated by law as the gravest of crimes.

from From Old English 'morthor,' meaning a secret or unlawful killing, rooted in the Proto-Germanic '*murthran' — a cousin of words for death across the Germanic family, all traceable back to a Proto-Indo-European root '*mer-' meaning 'to die.' The Old French 'murdre' later reinforced the spelling, and the lurking 'd' crept in over the centuries. Notably, the early Germanic sense carried the idea of secrecy or stealth — a killing concealed, distinct from open slaughter in battle — so the crime was named for its hiddenness from the very start.