| an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle. |
| a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison. |
decompression de·com·pres·sion (dē'kəm-prěsh'ən)
n.
The relief of pressure on a body part by surgery.
The restoration of deep sea divers and caisson workers to atmospheric pressure by means of a decompression chamber.