1.  ab(n = noun.communication) artium baccalaurens, ba, bachelor of arts - a bachelor's degree in arts and sciences;
is a kind of baccalaureate, bachelor's degree

2.  ab(n = noun.time) av - the eleventh month of the civil year; the fifth month of the ecclesiastical year in the Jewish calendar (in July and August);
is a kind of jewish calendar month
is a part of hebrew calendar, jewish calendar

3.  ab(n = noun.body) abdominal, abdominal muscle - the muscles of the abdomen;
is a kind of skeletal muscle, striated muscle
is a part of abdomen, belly, stomach, venter
has particulars: abdominal external oblique muscle, external oblique muscle, musculus obliquus externus abdominis, oblique, musculus transversalis abdominis, transverse muscle of abdomen, transversus abdominis, transversus abdominis muscle

4.  ab(n = noun.body) group ab, type ab - the blood group whose red cells carry both the A and B antigens;
is a kind of blood group, blood type

   The fifth month of the Jewish year according to the ecclesiastical reckoning, the eleventh by the civil computation, coinciding nearly with August. W. Smith. [1913 Webster]

ab, n. a human blood type of the ABO system.

ab, abbr.
1 able rating or seaman.
2 US Bachelor of Arts.

ab initio, ab ovo, fast of ab, group ab, ninth of ab, type ab