n. A person who hopes or seeks to keep some dangerous or unpleasant underground feature out of his or her neighborhood; the attitude of such a person.
Other Forms
In recent years, the greatest delays seem to be caused not by efforts to defraud the public but by attempts to placate it. Where the old water board once plowed over communities, the D.E.P. is now impeded by them. In 1993, when it tried to sink a shaft on East Sixty-eighth Street, Councilman Charles Millard protested that his office had received calls from parents whose children were "finding it difficult to concentrate." numby, or "not under my back yard," movements sprang up. In 1994, after engineers had spent two years planning a new shaft site, residents in Jackson Heights held a protest, carrying signs that said, "don't give us the shaft." Engineers were forced to find a new location. "When we want to choose a shaft site, everyone says, 'Oh, the water system is a miracle, but please find another place,' " Ward told me.
—David Grann, “City of water,” The New Yorker, September 01, 2003
Sir, — I have just learned that the proposed Dublin Port Tunnel will run 40 feet beneath my garden.

May I take this opportunity to declare myself a NUMBY — Not Under My Back Yard? — Yours, etc.
—John Little, “Underground movement,” Irish Times, January 10, 1996
1988 (earliest)
It's not a case of NIMBY, William Tardy says. The popular anti- development cry, which stands for Not In My Back Yard, just doesn't fit the facts of the supercollider proposal. For Tardy, opposing the project is a matter of NUMBY—Not UNDER My etc.

Tardy, the president of CATCH (Citizens Against The Collider Here), lives on a seven-acre farm outside St. Charles. The supercollider would indeed go under his back yard-as well as his front yard-if Illinois is chosen as the site for the project.
—Stevenson Swanson, “The Supercollider: Should it be built at Fermilab?,” Chicago Tribune, May 29, 1988