a.b.

noun1

1. •
   Able-bodied seaman.

phrase1

1. •
   Initialism of as before.

noun4

1. •
   (old-fashioned) A blank for a person's name, perhaps followed by C.D., etc. for others.

   • I, A.B., do swear that I will be faithful and bear true allegiance to Her Majesty Queen Victoria, Her heirs and successors according to law. So help me God! — 1900
2. •
   Initialism of artium baccalaureus (“Bachelor of Arts”).
3. •
   Initialism of able seaman or able-bodied seaman.
4. •
   Initialism of assembly bill.