The
method of
limits which includes
derivatives and
integrals is also known as
analysis. Judging from
Webster 1913's definition of calculus which is much broader, it seems that
analysis is a more
accurate term for this method.
In modern literature, 'calculus' is often used as a synonym for analysis, but apparently only for the more mainstream branches of real and vector variables. For instance complex analysis and tensor analysis retain the original term.
Webster 1913's broader definition is substantiated by the etymology of the word calculus. Originally its only meaning was stone or pebble, which when used in kinds of abacus gained a connection with mathematics.