/ əˌprɒksɪˈmeɪʃn; NAmE əˌprɑːk-/ noun
1.
an estimate of a number or an amount that is almost correct, but not exact :
That's just an approximation, you understand.
2.
approximation (of / to sth) a thing that is similar to sth else, but is not exactly the same :
Our results should be a good approximation to the true state of affairs.