<prompt> Not a disorder of form of thought is:TangentialityDerailmentThought BlockLoosening of association  <response>: C i.e. Thought Block Formal thought disorder typically refer to marked abnormalities in the form flow of or connectiity of thought; some clinicians use the term broadly to include any psychotic cognitive sign or symptoms. So broadly speaking all can be included in formal thought disorder but in tangentiality, loosening of association and derailment the form of thought is more disordered than thought blockQ. Kaplans CDTP In formal thought disorder, the structure or form of thought is disordered. It includes perseveration, flight of ideas clang association, puns, rhymes, loosening of associations, derailmentQ, vorbeireden, verbigeration word salad Oxford; tangentialityQ, transitory thinking, substitution, omission, drivelling, desultory thinking, neologism, povey of speech and povey of content Fish. Whereas thought block is mainly a disorder of flowstream of thoughtQ. 