let -
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"
prevent,
keep stop (someone or something) from doing something or being in a certain state; "We must prevent the cancer from spreading"; "His snoring kept me from falling asleep"; "Keep the child from eating the marbles"
pass travel past; "The sports car passed all the trucks"
let -
actively cause something to happen; "I let it be known that I was not interested"
cause,
induce,
stimulate,
have,
get,
make give rise to; cause to happen or occur, not always intentionally; "cause a commotion"; "make a stir"; "cause an accident"