Noah Webster
Quiddity
QUID'DITY, noun [Latin quid, what.]
1. A barbarous term used in school philosophy for essence, that unknown and undefinable something which constitutes its peculiar nature, or answers the question, quidest? The essence of a thing constitutes it tale quid, such a thing as it is, and not another.
2. A trifling nicety; a cavil; a captious question.