be on the loose
if a criminal or dangerous animal is on the loose, they have escaped from prison or from their cage

[TahlilGaran] Dictionary of Contemporary English ▲

on the loose
free to move about and dangerous.
Police warned that a serial killer is on the loose in the northwest.

[TahlilGaran] English Idioms Dictionary ▲

on the loose
to be free to go, to be not shut in or stopped by anything
The zoo animals were on the loose for three hours before the zookeeper discovered their escape.

[TahlilGaran] English Idioms Dictionary ▲

on the loose
adj. phr., informal Free to go; not shut in or stopped by anything.
The zookeeper forgot to close the gate to the monkey cage and the monkeys were on the loose.
All of the seniors were on the loose on "Senior Skip Day."

[TahlilGaran] English Idioms Dictionary ▲