loose2 [transitive] literary to make something unpleasant begin:
And now the anger Maggie had feared was loosed. to make
something loose or to untie someone or something, especially an
animal to fire an arrow, a bullet from a gun etc loose something
on/upon somebody/somethingphrasal verb to allow something
dangerous or harmful to begin to affect a situation or other
people: the evils loosed upon humanity in World War II