the word 'undue' is a straightforward english formation combining the native negative prefix 'un-' with the adjective 'due'. the core term 'due' has a rich lineage, tracing back to the latin verb 'debere', meaning "to owe", which itself is a compound of 'de-' (completely) and 'habere' (to have). entering english via old french, 'due' came to signify something that is owed, just, or proper. by prefixing 'un-', the word 'undue' was created to logically denote the opposite: something that is not owed, not proper, or exceeding what is just, thus giving rise to its modern meanings of being excessive or not yet payable.

Structure: un (not) + due (owed, appropriate) - un: a prefix of english origin, from old english 'un-', meaning "not". it functions as a negative or reversing particle. - due: from middle english 'dewe', from old french 'deu', past participle of 'devoir' (to owe), from latin 'debere' (to owe). it functions as the core adjective meaning "owed" or "appropriate".