aren't

[ahrnt, ahr-uh nt] /ɑrnt, ˈɑr ənt/
1.
contraction of are not.
2.
contraction of am not (used interrogatively).
Origin
as contraction of am not, a doublet of ain't (without raising of the vowel), spelling aren't by r-less speakers; ar was later substituted for the long a by speakers who regularly pronounce pre-consonantal r
Usage note
The social unacceptability of ain't, the historical contraction of am not, has created a gap in the pattern of verbal contractions. I'm not, the alternative to I ain't, has no corresponding interrogative form except ain't I. In questions, ain't I is often avoided by the use of aren't I: I'm right, aren't I? Aren't I on the list? This aren't is simply a different outcome of the same historical development that yielded ain't, but the fact that it is spelled and pronounced like the contraction of are not (as in You are staying, aren't you?) apparently gives it, for some, an acceptability that ain't lacks. The use of aren't I is objected to by others because a declarative counterpart, I aren't, does not exist. Many speakers, however, prefer aren't I to the uncontracted, rather formal am I not. See also ain't, contraction.
Examples from the web for aren't
  • We hear kids aren't cheap, and they stay that way, so she didn't want to spend a lot.
  • Although these eggs aren't widely available in stores, you can often find them at farmers' markets.
  • Rock concerts aren't generally known for their thought-provoking tranquillity.
  • It's easy to study the diversity of species here in part because there aren't all that many species to see.
  • His offensive moves, however, aren't those of a forward or a midfielder.
  • Then you might have a case where some of the people aren't exactly happy but that's rare.
  • People aren't jumping into the water unless a site is in danger or stands to advance research.
  • If the bubbles aren't properly protected, your meringue will never have much body.
  • The growers say their pumpkins aren't getting any smaller.
  • They would then take the information home to parents, who probably aren't aware of it either.
British Dictionary definitions for aren't

aren't

/ɑːnt/
contraction
1.
are not
2.
(informal, mainly Brit) (used in interrogative sentences) am not
Word Origin and History for aren't

1794, contraction of are not, originally written are'n't and generally so into early 19c.

If "ain't I?" is objected to, surely "aren't I?" is very much worse. [Lady Grove, "The Social Fetich," 1907]