ness

The suffix '-ness' is a native English element with deep Germanic roots, traceable to the Proto-Germanic abstract noun-forming suffix '-inassu-'. This suffix itself is a compound, likely derived from a combination of '-in-' (a suffix forming adjectives from nouns) and '-assu-' (an abstract noun suffix). It entered Old English as '-nes', '-nis', or '-nys', and was used prolifically to create nouns expressing a state or condition, such as 'goodness' from 'good' or 'darkness' from 'dark'. Its remarkable productivity and resilience have made it the primary and most common suffix in Modern English for forming abstract nouns from adjectives, outlasting other historical suffixes like '-th' (as in 'warmth') due to its regularity and clarity.

This is a suffix of Old English origin, from '-nes(s)', '-nis(s)', '-nys(s)'. Its functional role is to form abstract nouns from adjectives.