Guesstimate,

Definition of Guesstimate:

1. An estimate based on a mixture of guesswork and calculation.

2. Form an estimate of based on guesswork and calculation.

3. Approximation based on a mixture of broad assumptions and computations.

Synonyms of Guesstimate

Estimate, Calculate, Approximate, Make a guess at, Make an estimate of, Hypothesis, Theory, Prediction, Postulation, Conjecture