'ungentlemanly' originates from the prefix 'un-' meaning 'not' and the word 'gentlemanly,' which is derived from 'gentleman,' a term used to describe a man of good social standing.

'gentlemanly' evolved from the Middle English word 'gentilman,' which was influenced by the Old French 'gentil' meaning 'noble' and 'man.'

Initially, 'gentlemanly' meant 'noble or well-bred,' but over time it evolved to describe behavior befitting a gentleman.