Origins
Bold is one of the oldest words in English that still means roughly what it always has. Old English beald meant 'brave, confident, daring', and a thousand years later, bold means the same. Few words survive that long without major semantic drift.
It descends from Proto-Germanic *balþaz, with cognates across the Germanic languages. Old Norse ballr meant 'dire' or 'dangerous' — bold from the enemy's perspective. Dutch boud means 'daring'. German shifted most dramatically: bald now means 'soon', preserving the idea that a bold person acts quickly, without hesitation.
Proto-Indo-European Roots
The possible Proto-Indo-European root *bʰel- meant 'to swell'. If correct, boldness was originally imagined as a physical expansion — a swelling of the chest, a puffing up of courage. This connects bold to an unlikely relative: belly, from the same swelling root.
The name Archibald encodes the word's old meaning: Germanic *erka-balþaz, 'truly bold'. The typographic sense — bold type — arrived in the 19th century, drawing on the visual metaphor: thicker strokes look more assertive, more confident. Even in typography, bold means brave.