ferret

from The Century Dictionary.

• noun An artificial albinotic variety of the fitch or polecat, Putorius vulgaris or fœtidus, said to be of African origin, about 14 inches long, of a whitish or pale-yellowish color, with red or pink eyes, bred in confinement in Europe and America to kill rats, rabbits, and other vermin or small game living in holes, into which its lithe, slender, and sinuous body readily enters.
• noun In glass-manuf, the iron used to try the melted matter to see if it is fit to work, and to make the rings at the mouths of bottles.
• noun Originally, a silk tape or narrow ribbon used for fastening or lacing; now, a narrow worsted or cotton ribbon used for binding, for shoestrings, etc., and also, when dyed in bright colors, for cockades, rosettes, etc.
• To drive out of a lurking-place, as a ferret does the rabbit.
• Hence Figuratively, to search out by perseverance and cunning: commonly followed by out: as, to ferret out a secret.
• To search (a place).
• To worry, as a ferret does his prey.
• To hunt with ferrets: as, to ferret rats with trained ferrets.

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

• noun (Zoöl.) An animal of the Weasel family (Mustela furo syn. Putorius furo), about fourteen inches in length, of a pale yellow or white color, with red eyes. It is a native of Africa, but has been domesticated in Europe. Ferrets are used to drive rabbits and rats out of their holes. They are sometimes kept as pets.
• noun A kind of narrow tape, usually made of woolen; sometimes of cotton or silk; -- called also ferreting.
• transitive verb To drive or hunt out of a lurking place, as a ferret does the cony; to search out by patient and sagacious efforts; -- often used with out.
• noun (Glass Making) The iron used for trying the melted glass to see if is fit to work, and for shaping the rings at the mouths of bottles.

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

• noun An often domesticated mammal rather like a weasel, descended from the polecat and often trained to hunt burrowing animals.
• noun The black-footed ferret, Mustela nigripes.
• noun An diligent searcher.
• verb To hunt game with ferrets.
• verb To uncover and bring to light by searching; usually to ferret out.

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

• verb search and discover through persistent investigation
• verb hound or harry relentlessly
• noun domesticated albino variety of the European polecat bred for hunting rats and rabbits
• noun musteline mammal of prairie regions of United States; nearly extinct
• verb hunt with ferrets