The term 'call back' can be defined as a request to return or repeat something. This term can be expressed in several ways, such as ECHO (4 letters), RECALL (6 letters), REMEMBER (8 letters), RECANT (6 letters), RESCIND (7 letters), ENCORE (6 letters), RSVP (4 letters), and rephone (7 letters). ECHO is a repetition of sound, RECALL is the act of remembering something, REMEMBER is to retain knowledge of something, RECANT is to take back a statement, RESCIND is to revoke or cancel an order, ENCORE is a request for more, RSVP is an acronym for 'repondez s'il vous plaît' meaning 'please respond', and rephone is to call again.