Is “headlands” the right term for a land mass surrounded by water on three sides? And more specifically, would this (the town of Irondequoit, New York, north of Rochester) meet the criteria? The town is bounded by a river to the west, a bay to the east, and Lake Ontario to the north.
According to my Collegiate a headland is a point of land (usually high) sticking out into a body of water. It seems to me that the river to the west would disqualify Irondequoit.
There is no real definition of a headland as I understand it. It is the high area of the watershed of a river.
A peninsula for is surrounded by water on three sides. Further, if you go farther, all land in surrounded on water on three sides.