Copycat's activity is the act of imitating or mimicking someone else's behavior or actions. The two crossword solutions for this term are 'APERY' and 'aping'. APERY is defined as the act of imitating or copying something, while aping is defined as the act of imitating or mimicking someone else's behavior or actions. Both terms refer to the same concept, but with slightly different nuances. APERY is more general and can refer to any kind of imitation, while aping is more specific and refers to the act of imitating another person's behavior.