Merriam-Webster's Collegiate® Dictionary, 11th Edition
ESTIMATE
I. transitive verb (-mated; -mating)
Etymology: Latin aestimatus, past participle of aestimare to value, estimate
Date: circa 1532
1. archaic esteem , appraise ,
2. to judge tentatively or approximately the value, worth, or significance of, to determine roughly the size, extent, or nature of, to produce a statement of the approximate cost of, judge , conclude , estimative adjective Synonyms: see: estimate
II. noun
Date: 1552
the act of appraising or valuing ; calculation , an opinion or judgment of the nature, character, or quality of a person or thing ,
3. a rough or approximate calculation, a numerical value obtained from a statistical sample and assigned to a population parameter, a statement of the cost of work to be done