INTEGRATOR
integrator, planimeter
(noun) a measuring instrument for measuring the area of an irregular plane figure
Source: WordNet® 3.1
Etymology
Noun
integrator (plural integrators)
A person who, or a device which, integrates.
A device that calculates definite integrals.
Any electronic device that sums a measurement over time.
Source: Wiktionary
In"te*gra`tor, n. (Math. & Mech.)
Definition: That which integrates; esp., an instrument by means of which
the area of a figure can be measured directly, or its moment of
inertia, or statical moment, etc., be determined.
Source: Webster’s Unabridged Dictionary 1913 Edition