Verb (5-dan, く, intransitive)
1. to well (up); to gush out (of water); to spring out; to surge
岩の間からきれいな水が湧いている。Clear water is welling up from between the rocks.
2. to appear (esp. suddenly) (sweat, tears, etc.); to sweat; to cry
3. to feel emotions (e.g. joy, bravery, etc.); to spring up (e.g. an idea, emotions, clouds); to well up; to arise
どこからその自信が湧くんだか。I wonder where that confidence comes from.
4. to hatch; to breed; to propagate; to be infested (esp. of parasitic insects, etc.)
潰しても潰してもいつの間にか湧いてくる。No matter how many I squash, they keep breeding before I know it.