Source : Webster's Revised Unabridged Dictionary (1913)

Dipnoi \Dip"no*i\, n. pl. [NL., fr. Gr. ? ? with two breathing
   apertures; di- = di`s- twice + ? breath.] (Zo["o]l.)
   A group of ganoid fishes, including the living genera
   {Ceratodus} and {Lepidosiren}, which present the closest
   approximation to the Amphibia. The air bladder acts as a
   lung, and the nostrils open inside the mouth. See
   {Ceratodus}, and Illustration in Appendix.

Source : WordNet®

Dipnoi
     n : bony fishes of the southern hemisphere that breathe by a
         modified air bladder as well as gills; sometimes
         classified as an order of Crossopterygii [syn: {subclass
         Dipnoi}]