'acquainted' originates from Middle English, specifically the word 'aqueynten,' where 'a-' meant 'to' and 'queynten' meant 'to make known.'

'aqueynten' transformed into the modern English word 'acquaint' and eventually became 'acquainted' as an adjective.

Initially, it meant 'to make known,' but over time it evolved into its current meaning of 'having knowledge or experience of something or someone.'