Available Definitions:
1) n. - pl. of Pleuron.
2) n. fem. - The smooth serous membrane which closely covers the lungs and the adjacent surfaces of the thorax; the pleural membrane.
3) n. fem. - The closed sac formed by the pleural membrane about each lung, or the fold of membrane connecting each lung with the body wall.
4) n. fem. - Same as Pleuron.