Lewis & Short

nūdĭpĕdālĭa, ĭum, n. [nudipes].

  1. I. A religious procession of persons with bare feet, the barefoot festival, celebrated in seasons of great drought, to procure a fall of rain: cum stupet caelum et aret annus, nudipedalia denuntiantur, magistratus purpuras ponunt, fasces retro avertunt, precem indigitant, hostiam instaurant, Tert. Jejun. 16; id. Apol. 40; cf. Petr. 44; Sil. 3, 28.
  2. II. A going barefoot: nudipedalia exercere, Hier. in Ep. ad Galat. 4, 8.