Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
somnĭātor, ōris, m. [somnio], one who has faith in dreams; a dreamer, Sen. Contr. 3, 22, 15.
Of Joseph, Tert. adv. Gnost. 2 med.; Vulg. Gen. 37, 19; id. Zech. 10, 2.