Skepticism : The notion that the truth (about something) is difficult to find.
As stated, skepticism is relative to something, and does not deny there is truth to be established, but insists only that it is difficult to find. There have been various schools of Skepticism, some of which went further and denied that truth can be found. The problem with the stronger thesis is that it is self-defeating when asserted about any possible truth about anything: If it is true that no truth can be found, it must be false that no truth can be found, by plain logic. (Likewise, one cannot know that one knows nothing.)
When skepticism is taken in the moderate non-dogmatic sense it was defined, it generally is a wise, scientific, and sensible attitude, that is close to fallibilism. Indeed, about most things skepticism tends to be true, for the truth about most things, and certainly 'the truth, the whole truth, and nothing but the truth' is difficult to ascertain, and may take the work of many generations of the smartest men to establish.
Also it should be noted here that, in the moderate sense, one can be both skeptical and truthful, in that most of one's judgements will tend to be of the form 'I believe it is true that it is probable to such-and-such a degree that ...'. One may be quite certain about one's own uncertainty, and even so regard certain things one is uncertain of to be considerably more (or less) probable than not, on the basis of such evidence as one believes one has.
When skepticism is taken in a less moderate or less non-dogmatic sense, it looses its rational and skeptical flavour and orienation, and tends to turn into something quite different, namely relativism.
For relativists the normal position is something like 'anything goes' - any opinion (about something) is as good as any other opinion. This is difficult to combine consistently with moderate skepticism, because for relativists there tends to be no truth of the matter: All that counts, if anything, is how many people support an idea, regardless of the evidence or qualifications they have.
Another reason moderate skepticism and relativism tend to be inconsistent is that in fact there is nothing skeptical about relativism: It dogmatically and absolutely insists that all opinions (about something) are equally good, usually precisely because it likewise dogmatically and absolutely insists that there is no truth (of the supposed or of any kind). Thus, relativism tends to be a cheap and easy justification of wishful thinking.
Finally, it should be noted that moderate skepticism has no difficulty with admitting that some truths can be established quite easily, and indeed also that the judgment about certain subjects that the truth about these subjects is difficult to find is simply and unproblematically true (and usually can easily be supported with conclusive evidence, namely to the effect that there are diverse qualified and sincere persons with opposing ideas and inconclusive evidence for their ideas).