noun
: a saccular breathing organ occurring in many arachnids that contains numerous thin folds of membrane arranged like the leaves of a book through which gaseous exchange takes place
noun
: a saccular breathing organ occurring in many arachnids that contains numerous thin folds of membrane arranged like the leaves of a book through which gaseous exchange takes place
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012