Source : Webster's Revised Unabridged Dictionary (1913)

Eupnaea \Eup*n[ae]"a\, n. [NL., fr. gr. ? easy breathing; ? well
   + ? to breathe.] (Physiol.)
   Normal breathing where arterialization of the blood is
   normal, in distinction from dyspn[ae]a, in which the blood is
   insufficiently arterialized. --Foster.