Ought is a verb used to express correctness, duty, obligation, what the most expedient course of action should be. Ought is the correct verb form for all tenses. The negative of ought is formed in a highly irregular fashion for the English language: ought not. Ought comes to us in the late twelfth century from the Old English word, ahte.
Aught means 1.) anything at all, 2.) zero, nothing. Aught comes from the Old English awiht, which means anything, something. According to Ngram, use of the word aught has declined markedly since the beginning of the twentieth century.
“It ought to make you nervous,” Rosenstone told the audience of community leaders from throughout the region. (The Grand Forks Herald)
Glencore ought to lift the lid on its blackest box (Reuters)
Perhaps a decent chunk of these tens of billions of dollars in infrastructure funding ought to go to helping out some of these less-well-off communities. (The Times Colonist)
Homelessness in Utah is a statewide issue and ought not be the responsibility of one municipality or one county, Jackie Biskupski, the likely future mayor of Salt Lake City, told members of the Pioneer (The Deseret News)
“Well, it was nineteen-aught-twelve, and we were living six to a bed in North Fork, which is down by the Fork River, in Fork County.” (The Minneapolis Star-Tribune)
It didn’t matter that the jeans on the page were for women; I soon decided that the sun had set on my mid-aught days of wearing True Religion boot-cuts or Rock & Republic standard fits. (Vogue Magazine)
But, in the early aught years, the F.B.I.—which was struggling to regroup from having allowed the 9/11 hijackers to enter the country—was looking back through old immigration cases. (The New Yorker Magazine)