Flinch, recoil, and wince are all synonyms of quail, but each word has a slightly different use. When you flinch, you fail to endure pain or to face something dangerous or frightening with resolution ("she faced her accusers without flinching"). Recoil implies a start or movement away from something through shock, fear, or disgust ("he recoiled at the suggestion of stealing"). Wince usually suggests a slight involuntary physical reaction to something ("she winced as the bright light suddenly hit her eyes"). Quail implies shrinking and cowering in fear ("he quailed before the apparition").