The quality of resisting penetration by grease or oil; the state of being greaseproof.
From 'greaseproof' + '-ness'; this abstract noun takes the adjective describing an oil-resistant property and nominalizes it to discuss the condition itself.
Like 'greaselessness,' this is a technically valid but rarely needed word—most people just say 'this paper is greaseproof' rather than discussing 'the greaseproofness of the material,' but engineers and chemists might use it in technical writing.
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