Aught is a pronoun meaning anything whatever. Though the word has an archaic ring in the U.S., it is fairly common outside North America, especially in the U.K., where it’s a dialectal synonym of anything.
Aught is an ancient word. It goes back to Old English in various forms, and though it has taken many spellings over the centuries, its meaning has remained consistent through history. It means the same today as it did a thousand years ago, and unlike many other old words, it has not piled on secondary meanings. The Oxford English Dictionary lists a couple of definitions in addition to the first, but these are very rarely used.
Aught‘s old age and straightforward meaning notwithstanding, there is a relatively new tendency to use it in place of nought and naught—which mean, respectively, zero and nothing—especially in reference to the years between 2001 and 2009. In the U.S., people often describe the first decade of the 21st century as the aughts, and they might say, for instance, aught four for 2004. In this use, aught is synonymous with zero.
Aught is also not to be confused with ought, the synonym of should.
These writers use aught in its conventional sense:
Her hands are so exquisitely formed, so slender, one could imagine them breaking beneath aught heavier than a bit of chiffon. [quoted in The Daily Gleaner]
The drunk always believes that aught he does or says is witty. [Telegraph]
Irony: they’re despised for talking empty verbiage but they talk empty verbiage because their interrogators make aught else risk [Herald Scotland]
Aught vs. ought
Mistaken use of aught in place of ought, meaning should (with to) is surprisingly common. In each of these examples, aught should be changed to ought:
SANDAG will accept comments from the public on what kinds of items aught to be considered in the formal environmental impact report. [North County Times (link now dead)]
No doubt, the same policy will aught to extend in entire Manipur state by the department. [Kangla Online]
And those on medication for heart or blood pressure aught to remember taking it before the game. [KENS 5]
Of course, ought does have a rarely used secondary sense that makes it synonymous with nought, which by extension brings it close to aught, but that doesn’t change the fact that aught for ought as a synonym of should is a misspelling.