Căl'cu-lŭs, n.

n.; pl. CĂL'CU-LĪ. [Lat. calculus. See CALCULATE and CALCULI.]

1Sense 1. (Med.) Any hard, solid concretion, formed in any part of the body, but most frequent in the organs that act as reservoirs, and in the excretory canals; as, biliary calculi; urinary calculi, &c. Dunglison.

2Sense 2. (Math.) A method of computation.

Calculus of variations, a method in which the laws of dependence which bind the variable quantities together are themselves subject to change.—Differential calculus, a method of investigating mathematical questions by measuring the ratio of certain indefinitely small quantities called differentials. The problems are always of this form, to find how the change in some variable quantity alters at each instant the value of a quantity dependent upon it.—Integral calculus, a method which is the reverse of the differential, the object of which is to learn from the known ratio of the indefinitely small changes of two or more magnitudes, the relation of the magnitudes themselves, or, in other words, from having the differential of an algebraic expression to find the expression itself.—Imaginary calculus, a method of investigating the nature of quantities which are required to fulfill apparently impossible conditions, by which it is proved that every absurdity in geometry may be reduced to the attempt to measure a straight line in a direction different from that of its length;—so called because the quantities investigated are usually termed imaginary quantities. New Am. Cyc.