quin·o·lone / ˈkwinəˌlōn; ˈkwinlˌōn/ • n. any of a class of antibiotics used in treating a variety of mainly gram-negative infections, and thought to be responsible for antibiotic resistance in some microbes. Quinolones include the fluoroquinolones, which were developed later and contain fluorine.

quinolone (kwin-ŏ-lohn) n. one of a group of chemically related synthetic antibiotics that includes ciprofloxacin, nalidixic acid, and ofloxacin. These drugs are often useful for treating infections with organisms that have become resistant to other antibiotics.