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: Webster's Revised Unabridged Dictionary (1913)