Definition of 'User Acceptance Testing' Definition: User Acceptance Testing (UAT) is one of the last stages of the software development life cycle. 7 days ago · User Acceptance Testing (UAT) is a type of testing performed by the end user or the client to verify/accept the software system before moving. User Acceptance Testing (UAT) is the final stage of any software development life cycle. User Acceptance Testing (UAT), also known as beta or end-user testing, is defined as testing software by user or client to determine if it can be. User acceptance testing, a testing methodology where the clients/end users involved in testing the product to validate the product against their requirements. User acceptance testing (UAT) is the last phase of the software testing process.