n 1  :  the 1st letter of the Greek alphabet - symbol A or a  2  :  ALPHA PARTICLE  3  :  ALPHA WAVE
or  a-  adj 1  :  of or relating to one of two or more closely related chemical substances <the alpha chain of hemoglobin>  <a-yohimbine>  - used somewhat arbitrarily to specify ordinal relationship or a particular physical form, esp. one that is allotropic, isomeric, stereoisomeric, or sometimes polymeric (as in a-D-glucose)  2  :  closest in position in the structure of an organic molecule to a particular group or atom : also  :  occurring at or having a structure characterized by such a position <a-substitution>  .
 
 
 
Similar sounding terms:  alfa  alive  alv  alvei 
 
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