-ness
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 of -ness
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
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Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for -ness
-ness
suffix forming nouns
indicating state, condition, or quality, or an instance of one of thesegreatness; selfishness; meaninglessness; a kindness
Word Origin for -ness
Old English -nes, of Germanic origin; related to Gothic -nassus
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
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Word Origin and History for -ness
-ness
word-forming element denoting action, quality, or state, attached to an adjective or past participle to form an abstract noun, from Old English -nes(s), from West Germanic *in-assu- (cf. Old Saxon -nissi, Middle Dutch -nisse, Dutch -nis, Old High German -nissa, German -nis, Gothic -inassus), from *-in-, noun stem, + *-assu-, abstract noun suffix, probably from the same root as Latin -tudo (see -tude).
Online Etymology Dictionary, © 2010 Douglas Harper