un·less 
/ənˈlɛs/ conjunction
/ənˈlɛs/ conjunction — used to say what will happen, be done, or be true if something else does not happen, is not done, or is not true ▪ He will fail the course unless he gets a 90 on the exam. ▪ Unless something is done, the species will become extinct. ▪ I won't have an operation unless surgery is absolutely necessary. [=I will only have an operation if surgery is absolutely necessary] ▪ “Will I have to pay?” “Not unless [=only if] you want to.”
