(pl. calculuses) （亦作infinitesimal calculus）[mass noun] the branch of mathematics that deals with the finding and properties of derivatives and integrals of functions, by methods originally based on the summation of infinitesimal differences. The two main types are differential calculus and integral calculus.

(pl. calculuses) Mathematics & Logic a particular method or system of calculation or reasoning

(pl. calculi /-laɪ/) Medicine a concretion of minerals formed within the body, especially in the kidney or gall bladder