A chorus line is a large group of dancers who together perform synchronized routines, usually in musical theatre. Sometimes, singing is also performed. Chorus line dancers in Broadway musicals and revues have been referred to by slang terms such as ponies, gypsies and twirlies. A chorus girl or chorine is a performer in a chorus line (i.e. the chorus of a theatrical production), in contrast to terms such as chorist or chorister (a member of a choir).