Webster's Revised Unabridged Dictionary · 1913

Tetrapneumona

Tetrapneumona , noun, plural

[New Latin See Tetra-, and Pneumo-.]

(Zoology) A division of Arachnida including those spiders which have four lungs, or pulmonary sacs. It includes the bird spiders (Mygale) and the trapdoor spiders. See Mygale.