approximator
/ˌæprɒksəˈmeɪtər/Definitions
1. noun
A person or thing that approximates or estimates the value or quantity of something.
“The mathematician used an approximator to calculate the area of the irregularly shaped field.”
2. verb
To make an approximation or estimate of the value or quantity of something.
“The software approximator helps users to estimate the costs of their projects.”