1
                           general:: 
                            Phrase(s): on the side
1. Lit. extra, such as with a job or an additional order of food.  •  I would like an order of eggs with toast on the side, please.  •  She is a bank teller and works as a waitress on the side. 2. Fig. in addition to one’s spouse.  •  He is married, but also has a woman on the side.  •  She has boyfriends on the side, but her husband knows about them.
                        
                        
 
                        
                            McGrawhill's American Idioms And Phrasal Verbs
                        
                        
                    
                    
                        2
                           general:: 
                            1. In addition to the main portion of something; also, in addition to one's regular job. For example, He ordered some French fries on the side, or She often prepared tax returns on the side. [Second half of 1800s] 2. See ON SOMEONE'S SIDE; ON THE SIDE OF THE ANGELS.
                        
                        
 
                        
                            American Heritage Idioms