Triform is an uncommon word that describes something consisting of three forms or parts. If you want to express the idea of triformity in a different way, you could use synonyms such as tripartite, triplicate, or three-fold. Another possible option could be trifurcate, which refers to something that branches into three separate parts. Alternatively, you could opt for ternary, which describes something that is made up of three elements or components. Some other adjectives that might be relevant include triple, three-way, or tripled. By using these synonyms, you can vary your vocabulary and add more nuance to your writing.