An intelligence singularity is a singularity that may form in intelligent societies.
As societies become more intelligent they develop ways to more quickly increase their intelligence. For example, as we get more intelligent, computers, gene therapy, and other scientific breakthroughs may allow our society to reach levels of intelligence not yet dreamed of. Under the right circumstances (ie, the society does not collapse), intelligence may increase exponentially, and thus a singularity may occur.
An intelligence singularity may be equivalent to a complexity singularity.