the.com/horns

bone weaponry your skull grew because asking nicely never worked in nature

means The hard, pointed bony or keratinous growths that project from the heads of certain animals, used for defense and combat.

from From Old English 'horn,' tracing back to Proto-Germanic '*hurnaz' and the Proto-Indo-European root '*ker-' meaning 'head' or 'horn' — the same ancient root that branches into Latin 'cornu' (giving us 'unicorn' and 'cornet') and Greek 'keras.' It's one of those deep words that barely changed across millennia, because a pointy thing on a skull needed naming everywhere people met one.

never stops: true horns grow throughout an animal's entire life
hollow inside: horn surrounds a living bony core
both sexes: female bovids often wield horns too
not antlers: horns stay; antlers fall off yearly
rhino exception: rhino horn is matted hair, no bone

for instance

french horn — orchestral brass instrument with 3-4 valves, used since the 18th century

rhino horn — keratin structure on african black rhino and white rhino, weighs up to 3.5kg

narwhal tusk — single long spiral tooth of male narwhal in arctic waters, reaches 3 meters

texas longhorn cattle — breed with horns spanning up to 2.4 meters, iconic to texas ranching since 1800s