A hedgehog is a small brown animal with sharp spikes covering its back.
hedgehog in British English
(ˈhɛdʒˌhɒɡ)
noun
1.
any small nocturnal Old World mammal of the genus Erinaceus, such as E. europaeus, and related genera, having a protective covering of spines on the back: family Erinaceidae, order Insectivora (insectivores)
▶ Related adjective: erinaceous
2.
any other insectivore of the family Erinaceidae, such as the moon rat
3. US
any of various other spiny animals, esp the porcupine
hedgehog in American English
(ˈhɛdʒˌhɔg)
noun
1.
any of several small insectivores (family Erinaceidae) of the Old World, with a shaggy coat and sharp spines on the back, which bristle and form a defense when the animal curls up
2. US
the American porcupine
3.
a person regarded as being of a type that tends to see things in terms of a single, overarching viewpoint or philosophy
see also fox (sense 4)
4. Military
a.
any of several defensive obstacles
b.
any of a series of defensive fortifications capable of continued resistance after being encircled
Word origin
hedge + hog: prob. from living in hedgerows and from the hoglike snout