Also, let slide . Allow something to be ignored or to take or continue in its natural course. For example, Bill disagreed with Mary's description, but he let it ride , or He had a way of letting things slide . The first term, alluding to things moving along as though they were riding a horse or vehicle, dates from the early 1900s; the variant, using slide in the sense of “pass by,” dates from the late 1500s. Also see under let slip