Synonyms for Gully:

n.

dell, gorge, basin, gulch, canyon, box canyon, dale, glen, arroyo, gulley. crevice, cave, fissure, pothole, cavern, rift. ditch (noun)
crevasse, chasm.
groove (noun)
flute, channel, dado, ravine, trench, gutter, trough, corrugation, rut, slot, furrow, ditch, groove, incision, cut, canal.
ravine, ditch (noun)
crevasse, gutter, trench, chasm, channel.

Other synonyms:

cave, cavern, crevasse. pothole, chasm. gulch
canyon.
Other relevant words:
crevasse, glen, crevice, cavern, rift, fissure, chasm, gorge, dale, box canyon, arroyo, cave, dell, canyon, gulley, gulch, canal.

Usage examples for gully

  1. When she reached them, they were sprawled in the gully beside the path, now a muddy flood of water from the hill above. – Caribbee by Thomas Hoover
  2. At the top of the gully where Jack had met her before, she stopped, her eyes inquiring of every thicket near her. – The Lookout Man by B. M. Bower
  3. The gully trail had not been improved by the recent rains, and it taxed our animals severely to reach the summit. – In Indian Mexico (1908) by Frederick Starr