A/C

Abbreviation for "Air Conditioning" system. A device used in homes and automobiles which processes and circulates the air, thus making it cooler or warmer, generally by the use of some chemical, like Freon. Some folks call the warming function of the A/C a "heater", but it is part of the Air Conditioning system, unless it is provided by a furnace.

Alternating current. This is required for effectively turning electricity to kinetic energy. One type of current can cause a rotation up to 180 degrees. By alternating currents rapidly, there is a constant rotation back and forth over 180 degrees which can be converted to a more useful motion.

Abbreviation used by accountants and bookkeepers meaning "account." As used in a check, it has been held not a direction to the bank to credit the amount of the check to the person named, but rather a memorandum to identify the transaction in which the check was issued.