AO -abbr

  1. account of
  2. and others

AOK [,ā-(,)ō-'kā] -adv or adj

  1. very definitely OK

aor -abbr

  1. aorist

ao·rist ['ā-ə-rəst] -n, adj, adv

  1. an inflectional form of a verb typically denoting simple occurrence of an action without reference to its completeness, duration, or repetition

aor·ta [ā-'ȯr-tə] -n, adj

  1. the great arterial trunk that carries blood from the heart to be distributed by branch arteries through the body

aortic arch -n

  1. one of the arterial branches in vertebrate embryos that exist in a series of pairs with one on each side of the embryo, connect the ventral arterial system lying anterior to the heart to the dorsal arterial system above the alimentary tract, and persist in adult fishes but are reduced or much modified in the adult of higher forms

aor·tog·ra·phy [,ā-,ȯr-'tä-grə-fē] -n, adj

  1. arteriography of the aorta

aou·dad ['au̇-,dad, 'ä-u̇-] -n

  1. a wild bovine ( Ammotragus lervia) of No. Africa that is closely related to goats and sheep and has been introduced into the southwestern U.S. called also aoudad sheep, Barbary sheep