endangered species

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A species present in such small numbers that it is at risk of extinction.

from the GNU version of the Collaborative International Dictionary of English.

• noun A species of plant or animal that has declined in numbers to a point where further irreversible decline and extinction{3} has a significant chance. Lists of endangered species are maintained by government agencies, and in many cases the killing of such species or destruction of their habitat is prohibited by law.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A species which is in danger of becoming extinct.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a species whose numbers are so small that the species is at risk of extinction