to do sth or to happen in a way that is not controlled; to make a noise or remark, especially in a loud or sudden way
informal
to do sth or to happen in a way that is not controlled
Teenagers need a place to let loose.
let loose sth
to make a noise or remark, especially in a loud or sudden way
She let loose a stream of abuse.
let sb / sth loose
to free sb / sth from whatever holds them / it in place
She let her hair loose and it fell around her shoulders.
let sb / sth loose
to give sb complete freedom to do what they want in a place or situation
He was at last let loose in the kitchen.
Definiciones del Oxford Advanced Learner's Dictionary, 9.ª edición