chasm (n.)
- abysm
- abyss
- aperture
- arroyo
- blank
- breach
- break
- canyon
- cavity
- chap
- check
- chimney
- chink
- clearing
- cleavage
- cleft
- clove
- col
- crack
- cranny
- crater
- crevasse
- crevice
- cut
- cwm
- deep
- defile
- dell
- depth
- dig
- diggings
- dike
- disclosure
- ditch
- draw
- excavation
- fault
- fenestra
- fissure
- fistula
- flaw
- flume
- fontanel
- foramen
- fracture
- furrow
- gap
- gape
- gash
- gat
- gorge
- groove
- gulch
- gulf
- gully
- hiatus
- hole
- hollow
- incision
- inlet
- interval
- joint
- lacuna
- leak
- mine
- moat
- notch
- nullah
- opening
- orifice
- outlet
- overlook
- oversight
- pass
- passage
- passageway
- pit
- pore
- preterition
- quarry
- ravine
- rent
- rift
- rime
- rupture
- scissure
- seam
- shaft
- skip
- slit
- slot
- space
- split
- stoma
- trench
- valley
- void
- wadi
- well
- workings
- yawn