also: きょうまくこう
noun
pleural cavity
Anatomical term for the space between the two pleurae surrounding the lungs.
胸膜腔に液体がたまると呼吸が苦しくなることがある。
When fluid accumulates in the pleural cavity, breathing can become difficult.
胸膜 is the pleura (the membrane itself), while 胸膜腔 is the cavity or space between the pleural layers.
Compound of 胸膜 (pleura) + 腔 (cavity). The reading きょうまくくう is standard; きょうまくこう is a less common variant.