loosen

verb8

1. •
   To make loose.

   • After the Thanksgiving meal, Bill loosened his belt.
2. •
   To become loose.

   • I noticed that my seatbelt had gradually loosened during the journey.
3. •
   To disengage (a device that restrains).

   • At Liberty th’ unfetter’d Captive stands, And flings the loosen’d Shackles from his Hands. — 1717
4. •
   To become unfastened or undone.

   • Immediately my Shackles loosened and fell away of themselves […] — 1770
5. •
   To free from restraint; to set at liberty.

   • This is an admirable Rule; a Painter ought to have it perpetually present in his Mind and Memory. […] it loosens his hands, and assists his understanding. — 1695
6. •
   To relieve (the bowels) from constipation; to promote defecation.

   • […] Feare looseneth the Belly; because the Heat retiring inwards towards the Heart, the Gutts and other Parts are relaxed — 1626
7. •
   (no longer used) To create a breach or rift between (two parties).

   • I had rather lose the battle than that sister Should loosen him and me. — 1603
8. •
   (no longer used) To sail away (from the shore).

   • […] after the .iiii. day of oure arryuall in Britayne, the eightene shyps that we spake of before, which hadde the horsemen to conuey ouer, loosened from the further hauen with a soft wynd. — 1565