'bald' originates from Old English 'bald' (also written 'beald'), from a West Germanic/Proto-Germanic root that referred to a patch or whiteness; over time it became associated with lack of hair.

'bald' in Old English (e.g. 'bald') passed into Middle English as 'bald' and eventually became the modern English adjective and verb 'bald'; the verb form (to bald) is derived from the adjective meaning 'without hair.'

Initially, related senses pointed to a pale patch or exposed area; over time the primary sense shifted to 'without hair' or 'having had hair removed', which is the modern meaning.