Definition of book lung in English:

book lung

noun

Zoology
  • (in a spider or other arachnid) each of a pair of respiratory organs composed of many fine leaves. They are situated in the abdomen and have openings on the underside.

    • ‘Most spiders breathe through tracheae; some, like the wolf spiders, have both book lungs and tracheae.’
    • ‘A researcher at the University of Manchester has reported finding slit-like structures and book lungs on some eurypterid fossils.’
    • ‘Like spiders, they were terrestrial and respired through book lungs, and walked on eight legs.’
    • ‘Respiration takes place through the body surface, and/or by means of gills, tracheae, or book lungs.’