Wikipedia:

Serous membrane | serosa

Summary:

a smooth membrane consisting of a thin layer of cells which secrete serous fluid. Serous membranes line and enclose several body cavities, known as serous cavities, where they secrete a lubricating fluid which reduces friction from muscle movement. ...  (38 of 744 words, 4 images)

Link:

http://en.wikipedia.org/wiki/Serous membrane  [cite]

Britannica:

chorion | Serosa

Summary:

in reptiles, birds, and mammals, the outermost membrane around the embryo. It develops from an outer fold on the surface of the yolk sac. In insects ...  (26 of 100 words)

Link:

http://www.britannica.com/EBchecked/topic/114523/chorion  [cite]

Encarta:

serous membrane | serous membranes [plural] | serosa [anatomy] | serosae [anatomy, plural] | serosas [anatomy, plural]

Summary:

a thin moist transparent membrane that lines the body cavities and surrounds the internal organs, e.g. the peritoneum that lines the abdomen  (22 of 36 words)

Link:

http://encarta.msn.com/dictionary 1861718046/definition.html  [cite]

Random House:

serous membrane | serosa

Summary:

[zoology, anatomy] any of various thin membranes, as the peritoneum, that line certain cavities of the body and exude a serous fluid.  (22 of 27 words)

Link:

http://dictionary.infoplease.com/serous-membrane  [cite]

Merriam-Webster:

serous membrane

Summary:

a thin membrane (as the peritoneum) with cells that secrete a serous fluid | "serosa"  (14 of 24 words, 2 senses)

Link:

http://www.merriam-webster.com/dictionary/serous membrane  [cite]

Wiktionary:

serous membrane | serous membranes [plural] | serosa | serous tunic

Summary:

[anatomy] A thin membrane that secretes serum lining an internal body cavity, such as the peritoneum, the pericardium, and the pleura.  (21 of 22 words)

Link:

http://en.wiktionary.org/wiki/serous membrane  [cite]