The quality or state of being fitting, suitable, or appropriate; the condition of beseemingness.
From 'befitting' (participial adjective from befit) plus '-ness' (noun-forming suffix that turns adjectives into abstract nouns). The doubled suffix formation shows how English creates abstract qualities from relational verbs.
The word 'befittingness' is wonderfully redundant—it means 'the quality of being fitting' where 'fitting' already is an adjective meaning 'suitable'—yet it survives because it creates a delightfully formal, slightly archaic tone that Renaissance and Victorian writers loved for philosophical or ceremonial contexts.
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