'English-fluent' is a modern compound formed from the adjective 'English' (relating to the English language or England) and 'fluent' (able to speak or write a language easily).

'fluent' comes from Latin 'fluēns/fluēnt-' (present participle of 'fluere', 'to flow'), passed into Middle French and then Middle English as 'fluent' meaning 'flowing' and later 'flowing in speech'. 'English' derives from Old English 'Englisc', from the name of the Angles (Old English 'Englaland'). The compound 'English-fluent' is a descriptive formation in modern English combining these elements.

Originally 'fluent' meant 'flowing' (like a stream). Over time it shifted metaphorically to mean 'flowing in speech' and now commonly means 'able to speak or write a language easily and smoothly', as in 'English-fluent'.