
A^{2} 
abbreviation of "ampere" or "amperes," a unit of electrical current that refers to the quantity of current that passes through a resistor of one ohm when a potential of one volt is applied, equal to one coulomb per second. 
A^{3} 
abbreviation of "angstrom" or "angstroms," a unit of length equal to one hundredmillionth of a centimeter, used in measuring light waves. 
a.^{1} 
abbreviation of "acre" or "acres," a unit of area equal to 43,560 square feet or 4,047 square meters, used in measuring land. 
absolute zero 
the lowest possible temperature for any known substance, equal to 273.15 degrees Celsius or 459.67 degrees Fahrenheit. 
acre 
a unit of area equal to 43,560 square feet or 4,047 square meters, used in measuring land. [1/2 definitions] 
affirmative action 
a policy or program, supported by U. S. government regulations, to give equal opportunity in employment, college admissions, and the like to those considered previously disadvantaged, such as women and certain racial minority groups. 
ambidextrous 
able to use both hands with equal skill. 
ampere 
a unit of electrical current that refers to the quantity of current that passes through a resistor of one ohm when a potential of one volt is applied, equal to one coulomb per second. (abbr.: A, amp) 
angstrom 
(often cap.) a unit of length equal to one hundredmillionth of a centimeter, used in measuring light waves; angstrom unit. (abbr.: A, A.U.) 
approach 
to move in the direction of or become nearly equal to in quality, degree, or amount. [1/9 definitions] 
are^{2} 
a unit of area equal to one hundred square meters or 119.6 square yards. 
as^{2} 
an ancient Roman unit of weight equal to approximately twelve ounces; libra. [1/2 definitions] 
as good as 
equal to; the same as. 
associate 
linked with another or others and having equal or practically equal status. [1/10 definitions] 
astronomical unit 
a unit of length based on the average distance of the earth from the sun, equal to about 149.6 million kilometers or ninetythree million miles. 
astronomical year 
a unit of time equal to the period between one vernal equinox and the next. 
atomic mass unit 
a unit equal to one twelfth of the mass of an atom of the most abundant kind of carbon, equal to 1.6605 times 10^{24} gram. 
avdp. 
abbreviation of "avoirdupois," a system of weight based on a pound equal to sixteen ounces or to 453.59 grams. 
avoirdupois weight 
a system of weight based on a pound equal to sixteen ounces or to 453.59 grams. 
balance 
a state in which opposing forces are equal. [1/8 definitions] 
bar^{2} 
a unit of pressure equal to one million dynes per square centimeter. 

