Er·rat·ic a.
 1. Having no certain course; roving about without a fixed destination; wandering; moving; -- hence, applied to the planets as distinguished from the fixed stars.
    The earth and each erratic world.   --Blackmore.
 2. Deviating from a wise of the common course in opinion or conduct; eccentric; strange; queer; as, erratic conduct.
 3. Irregular; changeable. “Erratic fever.”
 Erratic blocks, gravel, etc. Geol., masses of stone which have been transported from their original resting places by the agency of water, ice, or other causes.
 Erratic phenomena, the phenomena which relate to transported materials on the earth's surface.