posology
In the works of English philosopher Jeremy Bentham (1748–1832): the study of quantity; mathematics.
historical, rare, uncountable
[page 253] [T]he branch of art and science therein denominated Posology, but commonly called Mathematics. […] [page 254] Of the two minor aggregates, into which, by this means, the major aggregate, Posology or Mathematics, was divided,—form-regarding, or figure-regarding Posology or Mathematics, in Greek-sprung language, Morphoscopic Posology, was the name given to the positive minor aggregate: […]
Where it comes from
From Ancient Greek πόσος (pósos, “how much?”) + -ology (suffix indicating a branch of learning).
Adapted from the Wiktionary entry posology (CC BY-SA 4.0).