A rigorous test or appraisal of the quality or worth of something.
In the 1960s, a party based around the use and advocacy of the psychedelic drug LSD ("acid").
The act of validating something.
Something, such as a certificate, that validates something; attestation, authentication, confirmation, proof or verification.
The process of identifying a new prisoner's gang affiliation.
The process whereby others confirm the validity of one's emotions.