a cavity or passage in a tubular organ; "the lumen of the intestine"
a unit of luminous flux equal to the amount of light given out through a solid angle of 1 steradian by a point source of 1 candela intensity radiating uniformly in all directions
a serve that strikes the net before falling into the receiver's court; the ball must be served again
leave unchanged; "let it be"
actively cause something to happen; "I let it be known that I was not interested"
make it possible through a specific action or lack of action for something to happen; "This permits the water to rush in"; "This sealed door won't allow the water come into the basement"; "This will permit the rain to run off"