'informally-acknowledged' originates from the combination of 'informal' and 'acknowledge'. 'Informal' comes from Latin 'informalis', meaning 'without form', and 'acknowledge' comes from Old English 'oncnawan', meaning 'to recognize'.

'informally-acknowledged' evolved from the combination of 'informal' and 'acknowledge', which were used separately in Middle English and later combined in modern English.

Initially, 'acknowledge' meant 'to recognize or admit', and 'informal' meant 'without formality'. Together, they evolved to mean 'recognized in a casual manner'.