'Loose' is an adjective, as in ' a box of loose screws'. The verb related to 'loose' is 'to loosen' and its past tense is 'loosened'.

A dark horse in a loose box is a classic idiom. It means that certain people are cunning and won't be contained by volatile situations.

A loose box is where a horse is not tied up and walk a full circle a stable is where the horse can only narrowly turn around

Figures that don't come with the original box.

Loose action figures are action figures that are out fo their box and are wrestlers might of or might not of been played with.