What does it mean to say an ethical theory is 'consequentialist'?

A consequentialist ethical theory holds that the primary consideration in assessing the moral value of an act is the moral value of the outcome or (set of) consequences that it produces. That is, the rightness or wrongness of a particular act depends on the goodness or badness of its consequences. An example of a consequentialist ethical theory is Utilitarianism, which asserts that the right act in any given circumstance is the one that maximises utility - in other words, it is the one that produces the most happiness to all concerned. Consequentialist ethical theories are often contrasted with deontological ethical theories, which claim that it is certain intrinsic features of an act, or of the rule governing that act, which determine its moral value. Hence, whereas a deontological ethical theory would (ordinarily) say that the act of killing is intrinsically wrong, a consequentialist theory would ordinarily say that killing is right in cases where it produces better consequences than not killing.