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").
A thing that serves to bear witness, confirm, or authenticate; validation, verification, documentation.
The process, performed by accountants or auditors, of providing independent opinion on published financial and other business information of a business, public agency, or other organization.
A confirmation or authentication.
An appearance in print or otherwise recorded on a permanent medium.