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.
2.
to form an opinion of; judge.
–verb (used without object)
3.
to make an estimate.
–noun
4.
an approximate judgment or calculation, as of the value, amount, time, size, or weight of something.
5.
a judgment or opinion, as of the qualities of a person or thing.
6.
a statement of the approximate charge for work to be done, submitted by a person or business firm ready to undertake the work.
To calculate approximately (the amount, extent, magnitude, position, or value of something).
To form an opinion about; evaluate: "While an author is yet living we estimate his powers by his worst performance"(Samuel Johnson).
n.
(-mĭt)
The act of evaluating or appraising.
A tentative evaluation or rough calculation, as of worth, quantity, or size.
A statement of the approximate cost of work to be done, such as a building project or car repairs.
A judgment based on one's impressions; an opinion.
[Latin aestimāre, aestimāt-.] es'ti·ma'tive adj., es'ti·ma'tor n.
Synonyms: These verbs mean to form a judgment of worth or significance. Estimate usually implies a subjective and somewhat inexact judgment: difficult to estimate the possible results in advance. Appraise stresses expert judgment: appraised the works of art. Assess implies authoritative judgment in setting a monetary value on something as a basis for taxation: assessing real estate for investors. Assay refers to careful examination, especially to chemical analysis of an ore: will assay the ingot. In extended senses appraise, assess, and assay can refer to any critical analysis: appraised his character; will assess the impact of higher taxes; assaying the idea's merit. Evaluate implies considered judgment in ascertaining value: evaluating a student's thesis for content and organization. Rate involves determining the rank or grade of someone or something in relation to others: rated the restaurant higher than any other in the city.
[v. es-tuh-meyt; n. es-tuh-mit, -meyt] 
verb, -mat⋅ed, -mat⋅ing, noun 
təˌmeɪt