A fling is a short period of enjoyment, especially the last one that you will get an opportunity to have. ...that last fling before you finally give up and take up a job. The meaning of FLING is to move in a brusque or headlong manner. How to use fling in a sentence. Synonym Discussion of Fling . FLING definition : 1. to throw or move something suddenly and with a lot of force: 2. a sexual relationship that is…. Learn more. FLING definition: 1. to throw something or someone suddenly and with a lot of force: 2. to move or do something…. Learn more.