Abyss, Aperture, Attend, Bore, Breach, Break, Broaching, Canyon, Cavity, Chap, Chasm, Check, Chimney, Chink, Clearing, Cleft, Stoma, Trench, Valley, Void, Wadi, Watch, Yaw, Yawn, Yawning, Col, Couloir, Crack, Crane, Cranny, Crevasse, Crevice, Cut, Defile, Dell, Disclosure, Ditch, Donga, Draw, Excavation, Eye, Fault, Fissure, Fistula, Flaw, Fontanel, Foramen, Fracture, Furrow, Gap, Gaping, Gash, Gawk, Gaze, Glare, Gloat, Glower, Gorge, Groove, Gulf, Gully, Hiatus, Hole, Hollow, Incision, Inlet, Inquire, Interrogate, Interval, Joint, Kloof, Lacuna, Leak, Look, Marvel, Moat, Notch, Ogle, Opening, Orifice, Outlet, Part, Pass, Passage, Passageway, Peer, Pore, Query, Question, Quiz, Ravine, Rent, Rift, Rime, Rubber, Rupture, Seam, Seek, Slit, Slot, Space, Split, Stare