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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