Definitions
1.nounA pouch or cavity in any organ or tissue, especially the paranasal sinus.
2.nounA channel for transmitting venous blood.
3.nounA notch or depression between two lobes or teeth in the margin of an organ.
4.nounAn abnormal cavity or passage such as a fistula, caused by the destruction of tissue.
5.nounA bay of the sea; a recess in the shore.