The word "copter" is a casual term for a helicopter, and there are several synonyms for it. Some of the popular alternatives to "copter" include "chopper," "helo," and "whirlybird." "Chopper" is a widely known and commonly used synonym for "copter" that is favored by the military and used in movies and TV shows. "Helo" is a shortened form of "helicopter," which is seen in formal and technical settings. "Whirlybird," on the other hand, is a cartoonish and playful term that is sometimes used by children or in comic strips. All of these synonyms share the same meaning with "copter" and offer writers and speakers a variety of options in expressing themselves.