The process or results of an assessment or appraisal in relation to stated objectives, standards, or criteria. In vocational education and training, may be applied to organisations, programs, policies, courses, etc.
Source: NCVER 2013, Australia

Evaluation (at project level) is a crucial phase for projects since it allows a review and qualitative and quantitative assessment of: 1) the results achieved against the aims (as regards activities/products), with implications for the whole of the grant if results are unacceptable and where results are very poor; 2) the means used to achieve these results in relation to the contractually agreed budget.Evaluation (at program level): evaluation in the Commission is defined as a judgement of interventions according to their results, impacts and the needs they seek to satisfy.
Source: EU Commission LLP 2007-2013, Europe

The systematic and objective assessment of an on-going or completed project, programme or policy, its design, implementation and results. The aim is to determine the relevance and fulfillment of objectives, development efficiency, effectiveness, impact and sustainability. An evaluation should provide information that is credible and useful, enabling the incorporation of lessons learned into the decision–making process of both recipients and donors.
Evaluation also refers to the process of determining the worth or significance of an activity, policy or program. An assessment, as systematic and objective as possible, of a planned, on-going, or completed development intervention.
Source: OECD 2010

Evaluation is the systematic and objective assessment of an ongoing or completed policy, plan, or programme, including its design, implementation, and results. It aims to assess the relevance and fulfilment of objectives and strategies with the intention of informing decision-making. ‘Formative’ evaluation relates to ongoing activities and helps guide implementation. ‘Summative’ evaluation assesses the results of a particular initiative, after completion.
Source: UNESCO IIEP/IBE;PEIC 2015, Global