Habitat. For the purposes of designating critical habitat only, habitat is the abiotic and biotic setting that currently or periodically contains the resources and conditions necessary to support one or more life processes of a species.
50 CFR § 424.02
The definitions contained in the Act and parts 17, 222, and 402 of this title apply to this part, unless specifically modified by one of the following definitions. Definitions contained in part 17 of this title apply only to species under the jurisdiction of the U.S. Fish and Wildlife Service. Definitions contained in part 222 of this title apply only to species under the jurisdiction of the National Marine Fisheries Service.