Glen is the word for a long, narrow valley. It traces its origin to 15th century Scottish Gaelic word Gleann.
crack
A door is an opening.
pit
Slim.
Chanelled into a narrow opening.
wide
slit
A crevice is a narrow crack or opening, a fissure or cleft.
Slot
The pharynx is the narrow opening at the back of the mouth. It is part of both the digestive system and the respiratory system.
spinal cord
crack!
The Mediterranean
The urethra.
Noun: # A narrow cut or opening; a slot. # (vulgar, slang) The opening of the vagina. # (vulgar, slang) A derogatory name for a woman, usually a sexually loose woman; a prostitute. Verb: # To cut a narrow opening. #: He slit the bag open and the rice began pouring out. # To split in two parts. It is also the word for "wear" in the Icelandic language.
Yes, waves can bend as they pass through a narrow opening. This phenomenon is known as diffraction. The degree of bending depends on the wavelength of the wave and the size of the opening.