comparator

/K AH0 M P ER1 AH0 T ER0/
noun
  1. 1

    Any device for comparing a physical property of two objects, or an object with a standard.

  2. 2

    An electronic device that compares two voltages, currents or streams of data.

  3. 3

    Anything that serves comparison

Source: https://en.wiktionary.org/wiki/comparator