Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
perplexor, āri (old inf. perplexarier; v. infra), v. dep. [perplexus], to make confusion, cause perplexity: scio, quo vos soleatis pacto perplexarier, Plaut. Aul. 2, 2, 81.