The hoary fox (Lycalopex vetulus), also called raposinha-do-campo (Portuguese for "meadow fox") or the hoary zorro^{[citation needed]}, is a species of zorro or "false" fox endemic to Brazil. Unlike many other foxes, it feeds primarily on small invertebrates such as insects.

The hoary fox has a short muzzle, small teeth, a short coat, and slender limbs. The upper part of the body is grey, and the underside of the body is cream or fawn. The tail is black on the tip with a marked dark stripe along the upper surface, which in male animals, may extend all the way along the back to the nape of the neck. The ears and outside part of the legs are reddish or tawny, and the lower jaw is black. Some melanistic individuals have also been reported.

It is small for a fox, weighing only 3 to 4 kilograms (6.6 to 8.8 lb), with a head and body length of 58 to 72 centimetres (23 to 28 in), and a tail 25 to 36 centimetres (9.8 to 14 in). Together with its slender form, the small size of the hoary fox makes it an agile and fast-running animal, while its relatively weak teeth adapt it to feeding on invertebrates, rather than larger prey.

Fox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids (slightly smaller than the medium-sized domestic dog), characterized by possessing a long narrow snout, and a bushy tail (or brush).

Members of about 37 species are referred to as foxes, of which only 12 species actually belong to the Vulpes genus of "true foxes". By far the most common and widespread species of fox is the red fox (Vulpes vulpes), although various species are found on almost every continent. The presence of fox-like carnivores all over the globe, together with their widespread reputation for cunning, has contributed to their appearance in popular culture and folklore in many societies around the world (see also Foxes in culture).

The Modern English word "fox" is Old English, and comes from the Proto-Germanic word fukh – compare German Fuchs, Gothic fauho, Old Norse foa and Dutch vos. It corresponds to the Proto-Indo-European word puk- meaning "tail of it" (compare Sanskrit puccha, also "tail"). The bushy tail is also the source of the word for fox in Welsh: llwynog, from llwyn, "bush, grove".Lithuanian: uodegis, from uodega, "tail", Portuguese: raposa, from rabo, "tail" and Ojibwa: waagosh, from waa, which refers to the up and down "bounce" or flickering of an animal or its tail. Male foxes are known as dogs or reynards, females as vixens, and young as kits, pups or cubs. A group of foxes is a "skulk", "leash", "troop" or "earth".