Cosplay definition in American English Illustrate costume play heart in easy language. Cosplay involves dressing up and pretending to be a particular character from an manga. It has become immensely popular among enthusiasts of geek culture around the world. Individuals carefully design costumes and accessories to accurately portray their favorite characters. Cosplayers often attend events or costume play events, where they can showcase their creativity and connect with others who share the same passion. In the end, costume play is an manifestation of appreciation and dedication for a fictional character and a love for the geek community.