differentiator

[ dif-uh-ren-shee-ey-ter ]
/ ˌdɪf əˈrɛn ʃiˌeɪ tər /

noun

a person or thing that differentiates.
Computers. an electronic device whose output signal is proportional to the derivative of its input signal.
Electricity, Electronics. a transducer or circuit (differentiator circuit) whose output is proportional to the rate of change of the input signal.

Origin of differentiator

First recorded in 1885–90; differentiate + -or2