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.