Cave, hole

窟 cavern N1 窯 kiln, oven, furnace N1 窃 stealth, steal, secret N1 窒 plug up, obstruct N1 窮 hard up, destitute, suffer N1 穴 hole, aperture, slit N1 窓 window, pane N2 突 stab, protruding, thrust N3 究 research, study N4 空 sky; empty N5