A

1. Elect. ampere; amperes.

2. Physics. angstrom.

3. answer.

4. Brit. arterial (used with a road number to designate a major highway): Take the A525 to Ruthin.

Symbol.

1. the first in order or in a series.

2. (sometimes l.c.) (in some grading systems) a grade or mark, as in school or college, indicating the quality of a student's work as excellent or superior.

3. (sometimes l.c.) (in some school systems) a symbol designating the first semester of a school year.

4. Music.

a. the sixth tone in the scale of C major or the first tone in the relative minor scale, A minor.

b. a string, key, or pipe tuned to this tone.

c. a written or printed note representing this tone.

d. (in the fixed system of solmization) the sixth tone of the scale of C major, called la.

e. the tonality having A as the tonic note.

5. Physiol. a major blood group, usually enabling a person whose blood is of this type to donate blood to persons of group A or AB and to receive blood from persons of O or A. Cf. ABO system.

6. (sometimes l.c.) the medieval Roman numeral for 50 or 500. Cf. Roman numerals.

7. Chem. (formerly) argon.

8. Chem., Physics. See mass number.

9. Biochem.

a. adenine.

b. alanine.

10. Logic. See universal affirmative.

11. Brit. a designation for a motion picture recommended as suitable for adults. Cf. AA (def. 5), U (def. 5), X (def. 9).

12. a proportional shoe width size, narrower than B and wider than AA.

13. a proportional brassiere cup size, smaller than B and larger than AA.

14. a quality rating for a corporate or municipal bond, lower than AA and higher than BBB.

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