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 testing period of time
A period of time when a person occupies a position only conditionally and may easily be removed for poor performance
A type of sentence where convicted criminals are allowed to continue living in the community but will automatically be sent to jail if they violate certain conditions