[dif-uh-ren-shee-ey-ter] 
| 1. | a person or thing that differentiates. |
| 2. | Computers. an electronic device whose output signal is proportional to the derivative of its input signal. |
| 3. | Electricity, Electronics. a transducer or circuit (differentiator circuit) whose output is proportional to the rate of change of the input signal. |
əˈrɛn