Cattishly is an adjective that describes someone who behaves in a snide or unpleasant manner, like a cat. Some other words that can be used as synonyms for cattishly include maliciously, spitefully, slyly, and snidely. These words all suggest a sense of cruelty or deviousness on the part of the individual in question. Other alternatives might include words like leeringly or tauntingly, which imply a certain level of mocking or teasing behavior. Ultimately, the best synonym for cattishly will depend on the context in which it is being used, and the specific nuance that the writer is trying to convey.