a native English suffix attached to adjectives and participles, forming abstract nouns denoting quality and state (and often, by extension, something exemplifying a quality or state): darkness; goodness; kindness; obligingness; preparedness.
Origin: Middle English, Old English -nes, -nis, cognate with German -nis,Gothic -(n)assus; suffix orig. *-assus; -n- by false division of words with adj. and past participle stems ending in -n-; compare Old English efnes (later efen-nys) evenness
suffix of action, quality or state, attached to an adj. or pp. to form a noun, from O.E. -nes(s), general W.Gmc., cf. M.Du. -nisse, O.H.G. -nissa, Ger. -nis, Goth. -inassus.