An evaluation of all the costs of the elements of a project or effort as defined by an agreed-upon scope . See order of magnitude estimate, budget estimate, and definitive estimate.
(Wideman Comparative Glossary of Common Project Management Terms v2.1 )
Other Definitions
Estimate – An assessment of the likely quantitative result. Usually applied to project costs and durations and should always include some indication of accuracy (e.g., + or – 15%). Usually used with a modifier (e.g., preliminary, conceptual, feasibility). Some application areas have specific modifiers that imply pre-set accuracy ranges (e.g., order of magnitude estimate, budget estimate, and definitive estimate in construction). (Wideman Comparative Glossary of Common Project Management Terms v2.1 )