How is 'quality' best defined?

The process of evaluating overall project performance on a regular basis to provide confidence that the project will satisfy the relevant quality standards.

The fitness for purpose or the degree of conformance of the outputs of a process or the process itself to requirements.

A. discipline for ensuring the outputs, benefits and the processes by which they are delivered meet stakeholder requirements and are fit for purpose.

The satisfaction of stakeholder needs measured by the success criteria as identified and agreed at the start of the project.