n 1 : the second letter of the Greek alphabet - symbol B or b 2 : BETA PARTICLE 3 : BETA WAVE
or b- adj 1 : of or relating to one of two or more closely related chemical substances <the beta chain of hemoglobin> <b-yohimbine> - used somewhat arbitrarily to specify ordinal relationship or a particular physical form and esp. one that is allotropic, isomeric, stereoisomeric, or sometimes polymeric (as in b- D-glucose) 2 : second in position in the structure of an organic molecule from a particular group or atom : also : occurring at or having a structure characterized by such a position < substitution> 3 : producing a zone of decolorization when grown on blood media - used of some hemolytic streptococci or of the hemolysis they cause .
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