To make loose.
After the Thanksgiving meal, Bill loosened his belt.
To become loose.
I noticed that my seatbelt had gradually loosened during the journey.
To disengage (a device that restrains).
To become unfastened or undone.
To free from restraint; to set at liberty.
To relieve (the bowels) from constipation; to promote defecation.
To create a breach or rift between (two parties).
To sail away (from the shore).
Having been made less tight or more relaxed.