to form an approximate judgment or opinion regarding the worth, amount, size, weight, etc., of; calculate approximately: to estimate the cost of a college education.
Definition: 2
to form an opinion of; judge.
Definition: 3
to make an estimate.
Definition: 4
an approximate judgment or calculation, as of the value, amount, time, size, or weight of something.
Definition: 5
a judgment or opinion, as of the qualities of a person or thing.