From Longman Dictionary of Contemporary Englishwhite-knuckledˌwhite-ˈknuckled adjective FRIGHTENEDif you have white-knuckled hands, your hands are held tightly in a fist because you are anxious or afraid
Examples from the Corpus
white-knuckled• One is myself, white-knuckled and terrified, as Jackie heads past the Casino towards the open sea at something like 150 m.p.h.• white-knuckled drivers• Isabel found her gaze fixed in unwilling fascination on one white-knuckled fist.• She saw his hands curl into white-knuckled fists and knew he was fighting to keep them at his sides.• I could feel strong mechanical tremors vibrating in many directions within my white-knuckled grasp.• Leonora gripped a rail with white-knuckled hands when the boat bucked as it met the wilder waters of the sound.• The hands that normally give the despatch box a confident caress gripped it in white-knuckled nervousness.• Rachel's hands were white-knuckled on the window-sill as she pictured it, vivid images burning into her mind. 