Utility: Being useful.
The term utility is used in philosophy, economics, law and some other disciplines primarily, it seems, to have a term that has few connotations while generally referring to anything which can satisfy some human want, and therefore has some positive value for some, and hence some use.
It seems often used in practice to make value-judgments and a language of recommendation and praise without seeming to do so, as in "the utility of cluster-bombing in the war-effort is self-evident".
Bentham was fond of its use, and defined it as follows in his "The Principles of Morals and Legislation":
By utility is meant that property in any object, whereby it tends to produce benefit, advantage, pleasure, good or happiness (all this is in the present case comes to the same thing), of (what comes again to the same thing) to prevent the happening of mischief, pain, evil, or unhappiness to the party whose interest is considered: if that party be the community, then the happiness of the community; if a particular individual, then the happiness of that individual.
This illustrates the confused, ambiguous or vague meaning of utility, while the parenthetical qualifications are typically Benthamistic: he would affirm it all comes to the same, but most others would deny or question that, say, "happiness" and "pleasure" "comes to the same thing".
Hume also used it quite a lot in his 'Enquiry concerning the Principles of Morals', apparently mostly because he wanted to avoid the religious connotations most words of praise of his time had, and because he was in need of some general term that expressed that so-and-so is good in some sense for someone.
See also Utilitarianism and Mill, and note that Mill claimed in effect that, at least for a decent utilitarian sort of person, the happiness of the individual and that of the community came to the same, essentially because, according to Mill, for a decent utilitarian sort of person, it was evident that the happiness of another was as important as the happiness of oneself, and one would not and should not count one's own good as anything special or preferable compared to the good of another.