| an extraordinary or unusual thing, person, or event; an exceptional example or instance. |
| an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle. |
| air embolism or aeroembolism | |
| —n | |
| See decompression sickness the presence in the tissues and blood of a gas, such as air or nitrogen bubbles, caused by an injection of air or, in the case of nitrogen, by an abrupt and substantial reduction in the ambient pressure | |
| aeroembolism or aeroembolism | |
| —n | |