rəˈkid.əˌmī, raˈk- noun plural
Usage: capitalized
Etymology: New Latin, from rachi- + -tomi (from Greek tomos cut, slice) — more at tome
: an order of Labyrinthodontia including most of the larger Permian amphibians and comprising forms having rhachitomous vertebrae, relatively stocky salamandriform bodies, and in some cases external gills