stuck

[stuckagain66]

membranous outer layer or lining of an organ bodily cavity

[JoolsTwo]

How many letters?

[stuckagain66]

-a-l

[novalis]

wall?

[stuckagain66]

Thank you

[gen2]

This question has also been answered previously as CAUL

[novalis]

Wall is defined as above in Chambers.

[solvitquick]

No it's NOT caul, it's WALL. In collin's UNABRIDGED dictionary wall is defined as: "any lining, membrane, or investing part that encloses or bounds a bodily cavity or structure etc. The definition of caul is far more specific: a portion of the amniotic sac sometimes covering a child's head at birth or large fold of the peritoneum hanging from the stomach across the intestines, the large omentum.
I thoroughly recommend you to spend about �40 on the unabridged Collins which is far more encyclopoedic than the concise version if you are serious about solving.