ERRATIC a.
Irregular; changeable. "Erratic fever." Harvey. 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.…
FOCUS n.
om a near object; -- so called because the positions of the object and its image are interchangeable. -- Focus tube (Phys.), a vacuum tube for Roentgen rays in which the cathode rays are focused upon the anticathode, for intensifying the effect. -- Principal, or Solar, focus (Opt.), the focus for parallel rays.…