The term 'Acid Test' is a phrase used to describe a test that is used to determine the authenticity of something. The two crossword solutions for this term are 'TRIAL' and 'PROOF'. A TRIAL is a process in which evidence is presented in a court of law to determine the guilt or innocence of an accused person. PROOF is evidence or argument that establishes or helps to establish a fact or the truth of a statement. Therefore, the Acid Test is a test that is used to determine the authenticity of something by presenting evidence and arguments to prove its validity.