Sine qua non

Latin term meaning "without which not." That without which thething cannot be; an absolutely essential and necessary thing. The followingexample shows how the term is used in law cases: Tom purchases a newrefrigerator. He puts the old one on the street to be carted away but does notremove the door or lock it shut. A child is severely injured when he is trappedinside the refrigerator. The sine qua non is Tom's failure to do somethingabout the door, which made the refrigerator an attractive nuisance.