Tentacool is a word used to describe a type of jellyfish-like Pokemon. The word is a combination of "tentacle" and "cool." For those looking for synonyms to use in their writing, "jellyfish," "urchin," "anemone," and "octopus" could be used instead. Each of these words describes a creature with tentacles or arms used for mobility and capturing prey. They also possess a unique coolness in their appearance or behavior. Ultimately, the choice of wording depends on the context and the writer's personal style.