- The highest rank on any of various scales that assign letters.
- The highest letter grade assigned (disregarding plusses and minuses).
- A tone three fifths above C in the cycle of fifths; the sixth tone of ...
- A tone three fifths above C in the cycle of fifths; the sixth tone of the C major scale; the first note of the minor scale of A minor; the reference tone that occurs at exactly 440 Hz; the printed or written note A; the scale with A as its keynote.
- A blood type that has a specific antigen that aggravates the immune response in people with type B antigen in their blood. They may receive blood from type A or type O but cannot receive blood from AB or B.
- Mass number.
- A universal affirmative suggestion.
- Acoustic source.
- Actual weight of an aircraft.
- Allele dominant.
- Ammunition examiner.
- Aspect ratio.
- Smallest of the brassiere cup sizes.
- Chemical activity.
- First van der Waals constant.
- Fraunhofer line for oxygen.
- Includes extras.
- Linear acceleration.
- Mean sound absorption coefficient.
- Shoe size narrower than B.
- Single A league, one of the lowest professional leagues.
- Total acidity.
- Adult; as used in film rating.
- An assist.
- Atom; atomic.
- One; any indefinite example of; used to denote a singular item of a group.
- One certain or particular; any single.
- The same; one.
- Any, every; used before a noun which has become modified to limit its scope;
- Someone or something like; similar to;
- In, on, at, by, towards, onto.
- In, into.
- Each, per, in, on, by.
- In, with.
- In the course of, experiencing.
- Engaged in.
- To, into.
- A meaningless syllable; ah.
- Distance from leading edge to aerodynamic center.
- specific absorption coefficient
- specific rotation
- allele (recessive)