The quality or state of being antipathetical; the characteristic of expressing strong natural dislike or opposition.
Nominalizing suffix -ness added to antipathetical, creating an abstract noun. This represents a deep layer of English word-building: turning adjectives about feelings into nouns that describe the existence of those feelings as properties.
This word barely exists in actual usage—it's theoretically valid but so unwieldy that even philosophers prefer saying 'the antipathetical nature of' or simply 'antipathy.' It shows English's generative capacity to create words even when speakers never actually need them.
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