a

the blood group whose red cells carry the A antigen ; the 1st letter of the Roman alphabet ; the basic unit of electric current adopted under the Systeme International d'Unites; "a typical household circuit carries 15 to 50 amps" ; a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation ; (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA ; one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose) ; any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes ;

a'man

the Israeli military intelligence which produces comprehensive national intelligence briefings for the prime minister and the cabinet ;

a-bomb

a nuclear weapon in which enormous energy is released by nuclear fission (splitting the nuclei of a heavy element like uranium 235 or plutonium 239) ;

a-horizon

the top layer of a soil profile; usually contains humus ;

a-line

women's clothing that has a fitted top and a flared skirt that is widest at the hemline; "it is called the A-line because the effect resembles the capital letter A" ;

a-list

a list of names of specially favored people; "the boss gave me his A-list of people we should try to recruit" ;

a-team

a group of elite soldiers or a leadership group of advisors or workers in an organization ;

a. a. michelson

United States physicist (born in Germany) who collaborated with Morley in the Michelson-Morley experiment (1852-1931) ;

a. a. milne

English writer of stories for children (1882-1956) ;

a. conan doyle

English author who created Sherlock Holmes (1859-1930) ;

a. e. burnside

United States general in the American Civil War who was defeated by Robert E. Lee at the Battle of Fredericksburg (1824-1881) ;

a. e. housman

English poet (1859-1936) ;

a. e. kennelly

United States electrical engineer noted for his work on the theory of alternating currents; independently of Oliver Heaviside he discovered the existence of an atmospheric layer that reflects radio waves back to earth (1861-1939) ;

a. e. w. mason

English writer (1865-1948) ;

a. noam chomsky

United States linguist whose theory of generative grammar redefined the field of linguistics (born 1928) ;

a. testudineus

a small perch of India whose gills are modified to allow it to breathe air; has spiny pectoral fins that enable it to travel on land ;

a.e.

Irish writer whose pen name was A.E. (1867-1935) ;

a battery

battery used to heat the filaments of a vacuum tube ;

a capella singing

singing without instrumental accompaniment ;

a cappella singing

singing without instrumental accompaniment ;

a horizon

the top layer of a soil profile; usually contains humus ;

a kempis

German ecclesiastic (1380-1471) ;

a la carte

a menu having individual dishes listed with separate prices ;

a level

the advanced level of a subject taken in school (usually two years after O level) ;

aa

an associate degree in arts ; an international organization that provides a support group for persons trying to overcome alcoholism ; a dry form of lava resembling clinkers ;

aaa

an aneurysm of the abdominal aorta associated with old age and hypertension ;

aachen

a city in western Germany near the Dutch and Belgian borders; formerly it was Charlemagne's northern capital ;

aaland islands

an archipelago of some 6,000 islands in the Gulf of Bothnia under Finnish control ;

aalborg

a city and port in northern Jutland ;

aalii

a small Hawaiian tree with hard dark wood ;

aalost

a town in central Belgium ;

aalto

Finnish architect and designer of furniture (1898-1976) ;

aar

a river in north central Switzerland that runs northeast into the Rhine ;

aardvark

nocturnal burrowing mammal of the grasslands of Africa that feeds on termites; sole extant representative of the order Tubulidentata ;

aardwolf

striped hyena of southeast Africa that feeds chiefly on insects ;

aare

a river in north central Switzerland that runs northeast into the Rhine ;

aare river

a river in north central Switzerland that runs northeast into the Rhine ;

aarhus

port city of Denmark in eastern Jutland ;

aaron

(Old Testament) elder brother of Moses and first high priest of the Israelites; created the golden calf ; United States professional baseball player who hit more home runs than Babe Ruth (born in 1934) ;

aaron's rod

tall-stalked very woolly mullein with densely packed yellow flowers; ancient Greeks and Romans dipped the stalks in tallow for funeral torches ;