lawn mower

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A machine with a rotating blade for cutting grass.

Century Dictionary and Cyclopedia

1. n. One who or that which mows a lawn; specifically, a machine, either pushed over the ground by hand or drawn by a horse, according to its size, for cutting the grass on a lawn. The lawn-mower consists essentially of a double edged spiral knife, or a series of spiral knives, set in the periphery of a cylinder, which is caused by gearing to rotate in contact with the edge of a stationary rectilinear knife placed tangentially to the cylinder at the height from the ground at which the grass is to be cut. The knives thus clip off the grass upon the principle of scissors.

Wiktionary

1. n. Any form of machine, having rotating blades, used to cut grass.
2. n. A person who mows lawns using a lawnmower.

GNU Webster's 1913

1. n. a machine for clipping the short grass of lawns.

WordNet 3.0

1. n. garden tool for mowing grass on lawns