Wild, in zoology or botany, is a rough if problematic antonym to domesticated: see wildlife. A wild animal is an animal that is not a domesticated animal — the common usage includes feral animals. A wildflower is, roughly speaking, a plant not of a garden variety .
The Wild, in the sense of places little affected by human activity, is also a difficult notion: see wilderness, wilderness area.
For further meanings, see wild card, Wild Hunt. On Where's George? a wild bill is one that has previously been entered and marked with the web address.