Douglas quailed when the dentist told him that he would need a root canal.
“There's an already notorious scene in a bathtub, involving the extraction of toenails, which would send Mary Whitehouse quailing ashen-faced for the exit, if she'd even made it that far.” — From a film review by Tom Robey in The (London) Telegraph, November 17, 2011
“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”).
From Merriam-Webster Online at www.Merriam-Webster.com.