Some terminology:
When we hear or read the word budget, we often think of a single numeric value representing the amount of money allocated for the completion of the project (such as “The project has a budget of 250 million Euros”), but that definition misses two important dimensions of the estimate: its time basis and its accuracy. The following definitions are taken from A Guide to the Project Management Body of Knowledge (PMBOK®) Guide, Third Edition and provide us with a more complete terminology for discussing baselines and control.

Baseline: The approved time-phased plan (for a project, a work breakdown structure component, a work package, or an activity), plus or minus approved scope, cost, schedule and technical changes. Usually used with a modifier (e.g., cost baseline, schedule baseline, performance measurement baseline).

Budget Estimate: see Estimate: A quantitative assessment of the likely amount or outcome. Usually applied to project costs, resources, effort, and durations and is usually preceded with a modifier (e.g., preliminary, conceptual, feasibility, order of magnitude, definitive). It should always include some indication of accuracy (e.g., ± x percent).