Meaning of CALCULUS in English

cal ‧ cu ‧ lus /ˈkælkjələs, ˈkælkjʊləs/ BrE AmE noun [uncountable]

[ Date: 1600-1700 ; Language: Latin ; Origin: 'small stone, piece of mineral that forms in the body, stone used in counting' , from calx ; ⇨ ↑ chalk 1 ]

the part of mathematics that deals with changing quantities, such as the speed of a falling stone or the slope of a curved line

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.