ab ab /ˌeɪ ˈbiː/

noun

1. The muscles of the abdomen  ( ab , abdominal , abdominal muscle )
   the muscles of the abdomen
    She did crunches every morning to strengthen her abdominal muscles
   She did crunches every morning to strengthen her abdominal muscles
   
   

 AB

1. () A bachelor's degree in arts and sciences  ( Artium Baccalaurens , BA , Bachelor of Arts , AB )
   a bachelor's degree in arts and sciences
   
2. The blood group whose red cells carry both the A and B antigens  ( AB , group AB , type AB )
   the blood group whose red cells carry both the A and B antigens
   

 Ab

1. The eleventh month of the civil year; the fifth month of the ecclesiastical year in the Jewish calendar (in July and August)  ( Ab , Av )
   the eleventh month of the civil year; the fifth month of the ecclesiastical year in the Jewish calendar (in July and August)