#opening.space__gap  an open or empty space in or between things; "there was a small opening between the trees"; "the explosion made a gap in the wall"
  supertype:  space.amorphous_shape  an empty area (usually bounded in some way between things); "the architect left space in front of the building"; "they stopped at an open space in the jungle"; "the space between his teeth"
  part of:  Earth's_surface
  subtype:  Ranvier's_nodes__nodes_of_Ranvier  small gaps in the myelin sheath of medullated axons
  subtype:  foramen__hiatus  a natural opening or perforation through a bone or a membranous structure
     subtype:  interventricular_foramen__foramen_of_Monro__Monro's_foramen  the small opening (on both the right and left sides) that connects the third ventricle in the diencephalon with the lateral ventricle in the cerebral hemisphere
     subtype:  foramen_magnum__foramenmagnum  the large opening at the base of the cranium through which the spinal cord passes
  subtype:  breach.opening  an opening (especially a gap in a dike or fortification)
  subtype:  chasm  a deep opening in the earth's surface
     subtype:  abyss__abys  a bottomless gulf or pit
     subtype:  gulf.chasm  a deep wide chasm
  subtype:  scissure__crack__cleft__crevice__fissure  a long narrow opening
     subtype:  chap.scissure  a crack in a lip caused usually by cold
     subtype:  chink  a narrow opening as e.g. between planks in a wall
     subtype:  crevasse  a deep fissure
     subtype:  fatigue_crack__fatiguecrack  a crack in metal resulting from metal fatigue
     subtype:  geological_fault__fault__shift__fracture__break  (geology) a crack in the earth's crust resulting from the displacement of one side with respect to the other; "they built it right over a geological fault"
        subtype:  Denali_Fault  a major open geological fault in Alaska
        subtype:  inclined_fault  a geological fault in which one side is above the other
           subtype:  normal_fault__gravity_fault__common_fault  an inclined fault in which the hanging wall appears to have slipped downward relative to the footwall
           subtype:  thrust_fault__overthrust_fault__reverse_fault__reversefault  a geological fault in which the upper side appears to have been pushed upward by compression
        subtype:  strike-slip_fault  a geological fault in which one of the adjacent surfaces appears to have moved horizontally
        instance:  San_Andreas_Fault
     subtype:  rift.scissure  a narrow fissure in rock
     subtype:  slit.scissure  a narrow fissure
     subtype:  split.scissure  a lengthwise crack in wood; "he inserted the wedge into a split in the log"
     subtype:  vent.scissure__volcano  a fissure in the earth's crust (or in the surface of some other planet) through which molten lava and gases erupt
     subtype:  volcanic_crater__crater  a bowl-shaped opening at the top of a volcano
        subtype:  caldera  a large crater caused by the violent explosion of a volcano that collapses into a depression
        subtype:  maar  a flat-bottomed volcanic crater that was formed by an explosion; often filled with water
  subtype:  hole.opening  an opening into or through something
     subtype:  aperture.hole  an opening in something
        subtype:  pupil  contractile aperture in the iris of the eye
        subtype:  micropyle  minute opening in the wall of an ovule through which the pollen tube enters
        subtype:  stoma.aperture__pore  a minute epidermal pore in a leaf or stem
     subtype:  bolt-hole  a hole through which an animal may bolt when pursued into its burrow or den
     subtype:  bullet_hole  a hole made by a bullet passing through it
     subtype:  cranny  a small opening or crevice (especially in a rock face or wall)
     subtype:  leak.hole  an accidental hole that allows something (fluid or light etc.) to enter or escape; "one of the tires developed a leak"
     subtype:  ozone_hole__ozonehole  an area of the ozone layer (near the poles) that is seasonally depleted of ozone
     subtype:  perforation.hole  a hole made in something; "a perforation of the eardrum"
     subtype:  rathole  a hole (as in the wall of a building) made by rats
     subtype:  knothole  a hole in a board where a knot came out
  subtype:  mouth-like_space_opening__mouth  an opening that resembles a mouth (as of a cave or a gorge); "he rode into the mouth of the canyon"; "they built a fire at the mouth of the cave"
  subtype:  rift  a gap between cloud masses; "the sun shone through a rift in the clouds"
  subtype:  rip__rent__split__tear  an opening made forcibly as by pulling apart; "there was a rip in his pants"
  subtype:  window.opening  an opening that resembles a window in appearance or function; "he could see them through a window in the trees"

No statement uses or specializes opening.space; click here to add one.