Siredon \Si*re"don\, n. [NL., from Gr. ??? a siren.] (Zo["o]l.) The larval form of any salamander while it still has external gills; especially, one of those which, like the axolotl ({Amblystoma Mexicanum}), sometimes lay eggs while in this larval state, but which under more favorable conditions lose their gills and become normal salamanders. See also {Axolotl}.