'protuberant' originates from Latin, specifically the word 'protuberans' (from the verb 'protuberare'), where 'pro-' meant 'forward' and 'tuber' meant 'lump' or 'swelling'.

'protuberant' changed from Late Latin 'protuberans' (present participle of 'protuberare') and eventually became the modern English word 'protuberant' via Medieval/Late Latin usage entering English.

Initially, it meant 'being in a state of forming a swelling or lump,' and over time it has come to mean more generally 'bulging or projecting outward.'