These words all refer to the idea that something is in fact what it is represented to be. In this sense genuine is the most general of this group of words, and applies to anything having the origin, authorship or character claimed for it: a genuine example of cuneiform inscription; a genuine painting by Goya; a genuine bargain. Sometimes the informal word dinkum , is used in these senses of genuine , but it is mostly kept for adverbial use to assure one of the truth of something: It’s a fact, fair dinkum . Authentic is often interchangeable with genuine : an authentic (or genuine ) antique. But authentic emphasizes formal proof or documentation that an article is what it is claimed to be, whereas genuine simply asserts that the article is not spurious, adulterated or counterfeit.

• The geologists declared the fragment to be an authentic specimen of a rare fossil; an authentic Utrillo, verified by several art connoisseurs; an authentic replica of the drawing; genuine silver, unmixed with baser metals.

Actual means existing in fact, not imaginary, and is synonymous with one sense of real : an actual (or real ) event in history. Actual , however, need not refer to physically existent things, whereas real usually does in this sense: an actual change in the rules; It was a real person, not someone invented in a dream. Real also means being in accordance with appearance or claim, not artificial or counterfeit, and is in this sense often synonymous with genuine : a real (or genuine ) alibi; real (or genuine ) money. The emphasis on appearance sometimes distinguishes real from genuine : a real feast (i.e., a meal having the aspect of a feast); a real lecher (i.e., a person having the appearance or manner of a lecher). Genuine , if used in these examples, would convey a more conspicuous sense of personal style and a greater degree of informality.

True means being real or natural : a true specimen; true gold. In many context it is interchangeable with real , and often with genuine as well: a true (or real ) feast; a true (or real or genuine ) solution to a problem. Note that true in some contexts, as in a true alibi, is ambiguous, in that it can mean either conforming to the facts of the matter (i.e., with the truth) or being in accordance with the appearance of a genuine alibi (i.e., not appearing spurious or contrived.) Obviously, a true alibi in the latter sense may well be false in actual fact.