Relating to or characteristic of a benefactor; showing the quality of giving benefits or doing good.
From Latin benefactorius, derived from benefactor 'one who does good.' The -ory suffix (as in factory, oratory) creates adjectives meaning 'relating to' or 'having the nature of.' The word evolved to describe things pertaining to benefactors.
You almost never see this word in modern writing—it's been mostly replaced by 'beneficent'—but it shows how Renaissance scholars loved creating parallel adjective forms for every noun, creating a lost landscape of forgotten vocabulary.
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