See also: Appendix:Variations of "aa"
- achievement age
- amino acid
- antiaircraft; antiaircraft artillery
- associate in accounting (a degree)
- associate of arts / associate in arts (a degree)
- Thomas, Clayton L. (1993)
- Thomas, Clayton L., editor (1940) Taber's Encyclopedic Medical Dictionary, 5th edition, Philadelphia, PA: F. A. Davis Company, published 1993, →ISBN, page 1