Plainedge (previously known as Turkeyville)[2][3] is a hamlet and census-designated place (CDP) on the South Shore in the Town of Oyster Bay in Nassau County, on Long Island, in New York, United States.

Plainedge was originally acquired from Marsapeque Indian chiefs Sowwamacus, Wm Choppy, Soureekenny, Wamassum, Sascomoma and Ruampass land as part of the Bethpage Purchase of 1687 by Thomas Powell of the Huntington settlement.

[4][5] The first of note came in 1690, through the efforts of eighteen joint ventures, with the purchase of the "West Neck" that occupied the western arena of Plainedge.

In 1694, William Frost purchased all land south of Boundary Avenue, which was gifted to him by Indians Chippie, Maomie and Seruckon.

Through the efforts of Powell, the "Rim of the Woods Purchase"[6] of 1699 acquired the remaining land in the northern section of Plainedge (Boundary Avenue, north to Old Motor Parkway, and Hicksville Road east to Cedar Drive).

According to the United States Census Bureau, the CDP has a total area of 1.4 square miles (3.6 km2), all land.

Because Plainedge is not incorporated as an official town within Nassau County, residents are served by the Bethpage (11714), Massapequa (11758), Seaford (11783), Farmingdale (11735), and Levittown (11756) Post Offices.