Lewis & Short

spīrābĭlis, e, adj. [spiro], that may be breathed, good to breathe, breathable, respirable.

  1. I. Lit.: terra circumfusa undique est hac animali spirabilique naturā, cui nomen est aër, Cic. N. D. 2, 36, 91; cf. id. ib. 2, 6, 18; id. Tusc. 1, 17, 40; 1, 29, 70.
  2. II. Transf.
    1. * A. Pass., that serves to sustain life, vital: per sidera testor, caeli spirabile lumen, Verg. A. 3, 600.
    2. * B. Act., that can breathe, fitted for breathing, respiratory: viscera, Plin. 9, 7, 6, § 17.