Ahi ahi m. ( {aMh}) , a snake the serpent of the sky, the demon Vritra RV. ; (see also {ahirbudhnyas} a cloud water the sun of Rahu a traveller the navel lead (in arithm.) the number eight N. of a Rishi (with the patron. {auzanasa}) and of another (with the patron. {paidva}). [Zd. {azi} ; Lat. {angui-s} ; Gk. ; Lith. {ungury-s} ; Russ. ;Armen. {oz} ; Germ. {unc}.] Ahi cf. Azi as in Azi Dahaka
 Vritra was also known in the Vedas as Ahi ("snake"), and he is said to have had three heads. http://www.reference.com/browse/dragon+castles