ART - Human effort to imitate, supplement, alter, or counteract the work of nature.
HAT - A covering for the head, often in the approximate form of a cone or a cylinder closed at its top end, and sometimes having a brim and other decoration.
RAT - A medium-sized rodent belonging to the genus Rattus.
RAW - Of weather: unpleasantly damp or cold.
TAR - A black, oily, sticky, viscous substance, consisting mainly of hydrocarbons derived from organic materials such as wood, peat, or coal.
WAR - Organized, large-scale, armed conflict between countries or between national, ethnic, or other sizeable groups, usually involving the engagement of military forces.
TART - Sharp to the taste; acid; sour.
THAT - The (thing) being indicated (at a distance from the speaker, or previously mentioned, or at another time).
WHAT - Which thing, event, circumstance, etc.: used interrogatively in asking for the specification of an identity, quantity, quality, etc.
WART - A type of deformed growth occurring on the skin caused by the human papillomavirus (HPV).
WATT - In the International System of Units, the derived unit of power; the power of a system in which one joule of energy is transferred per second.
THAW - To melt, dissolve, or become fluid (specifically by gradual warming); to soften; said of that which is frozen.
HART - A male deer, especially the male of the red deer after its fifth year.
WRATH - Great anger.
THWART - To prevent; to halt; to cause to fail; to foil; to frustrate.