ART - Human effort to imitate, supplement, alter, or counteract the work of nature.
OAR - An implement used to propel a boat or a ship in the water, having a flat blade at one end, being rowed from the other end and being normally fastened to the vessel.
RAT - A medium-sized rodent belonging to the genus Rattus.
ROT - To suffer decomposition due to biological action, especially by fungi or bacteria.
TAR - A black, oily, sticky, viscous substance, consisting mainly of hydrocarbons derived from organic materials such as wood, peat, or coal.
TOO - Likewise.
OAT - Widely cultivated cereal grass, typically Avena sativa.
TOT - A small child.
ROAR - To make a loud, deep cry, especially from pain, anger, or other strong emotion.
ROOT - The part of a plant, generally underground, that absorbs water and nutrients.
TART - Sharp to the taste; acid; sour.
TORT - Tart, sharp.
TROT - A gait of a four-legged animal between walk and canter, a diagonal gait (in which diagonally opposite pairs of legs move together).
TOOT - The noise of a horn or whistle.
ROTOR - A rotating part of a mechanical device, for example in an electric motor, generator, alternator or pump.
TAROT - A card game played in various different variations.
ORATOR - Someone who orates or delivers an oration.
ROTATOR - One that rotates.