'acknowledgingly' originates from English, specifically formed from the verb 'acknowledge' plus the suffixes '-ing' and '-ly', where 'acknowledge' provided the root meaning and '-ing' + '-ly' turned it into an adverbial form.

'acknowledge' developed in Middle English as 'aknowlegen' (or similar spellings) from older Germanic/Old English roots such as 'cnawan'/'oncnawan' meaning 'to know'; over time the verb took the modern form 'acknowledge', and later morphological additions produced 'acknowledging' and then 'acknowledgingly'.

Initially related to the basic idea 'to know' or 'to recognize', the sense shifted toward 'to admit or recognize (the truth, existence, or importance of)' and the adverbial form now means 'in a manner that shows such recognition or admission'.