If you accept that anarcho-capitalism is a form of anarchism, then it falls under the larger umbrella term 'individualist anarchism'. After being involved in discussions on here about ana-cap, and talking with self-declared anarcho-capitalists, I've come to agree with the idea that some who claim that label are actually anarchists, and others are merely extremist neoliberals; the source of confusion being that anarcho-capitalism is coming from a pro-market, usually American perspective, and as such they tend to use pro-market liberal vocabulary rather than anarchist vocabulary. In anarchist terms, 'capitalism' is an exploitative mode of production that rests on wage slavery; to anarcho-capitalists, 'capitalism' refers only to free markets and possession of property (liberal vocabulary doesn't usually differentiate between personal and private property).
So it is possible that someone who claims the label 'anarcho-capitalist' is an anarchist, in which case you could describe them, using anarchist vocabulary, as an individualist anarchist, market anarchist, (potentially) natural-rights anarchist etc.
Rice Boy's answer covers what 'individualist anarchism' can mean pretty thoroughly and I don't feel the need to add much more on that. It might be worth re-emphasizing though, that these different ideological terms are just tools for talking about different ideas that synergize or have some kind of affinity with each other, and what that means to actual people - anarcho-capitalism and individualist anarchism don't exist when we're not using them to describe ourselves and our ideas.
Edit: Oh also, you might find Sidney Parker's 'My Anarchism' (http://www.la-articles.org.uk/FL-2-2-5.pdf
) interesting, it's a short account of his abandonment of social anarchism in favor of egoist individualism, and it's a good illustration of some of the ideas at work here.