any of various members of a genus (Ambystoma) of dark salamanders of Mexico and the W U.S. that mature sexually and breed while remaining in the gilled larval stage due to a thyroid deficiency
See axolotl in American Heritage Dictionary 4
(ăkˈsə-lŏtˌl)
noun
Any of several salamanders (genus Ambystoma) native to Mexico and the western United States that, unlike most amphibians, often retain their external gills and become sexually mature without undergoing metamorphosis.