Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
trĭformis, e, adj. [ter-forma], having three forms, shapes, or natures; threefold, triple, triform (poet.): Chimaera, Hor. C. 1, 27, 23: canis, i. e. Cerberus, Sen. Herc. Oet. 1202: Geryon, id. Agam. 841: diva, i. e. Diana, who was also Luna and Hecate, Hor. C. 3, 22, 4; called also triformis dea, Ov. M. 7, 94: mundus, because composed of air, earth, and water, id. ib. 15, 859.