cal‧cu‧lus /ˈkælkjələs, ˈkælkjʊləs/ noun [uncountable]
[Date: 1600-1700; Language: Latin; Origin: 'small stone, piece of mineral that forms in the body, stone used in counting', from calx; ⇒ chalk¹]
the part of mathematics that deals with changing quantities, such as the speed of a falling stone or the slope of a curved line

[TahlilGaran] Dictionary of Contemporary English ▲