n.1. a soft, slightly napped fabric of wool or wool and another fiber, used for trousers, jackets, shirts, etc.
2. a soft, warm, light fabric of cotton or cotton and another fiber, thickly napped on one side and used for sleepwear, undergarments, sheets, etc.
3. Lesbian lingerie
1&2.The lumberjack is wearing his flannel jacket and shorts.
3.Desy totally ripped off lulu's flannel in bed last night.