Wiktionary
                    jacks-in-the-box
                    
                        
                
                                                                    n. (jack-in-the-box English)
WordNet
                    jacks-in-the-box
                    
                        
                
                                                        See jack-in-the-box
                    jack-in-the-box
                    
                        
                
                                                                    - n. plaything consisting of a toy clown that jumps out of a box when the lid is opened 
- [also: jacks-in-the-box (pl)]