a 1 or A (ā)
n. pl. a's or A's also as or AsIdiom:
1. The first letter of the modern English alphabet.
2. Any of the speech sounds represented by the letter a.
3. The first in a series.
4. Something shaped like the letter A.
5. A The best or highest in quality or rank: grade A milk.
a. The sixth tone in the scale of C major or the first tone in the relative minor scale.
b. A key or scale in which A is the tonic.
c. A written or printed note representing this tone.
d. A string, key, or pipe tuned to the pitch of this tone.
7. A One of the four major blood groups in the ABO system. Individuals with this blood group have the A antigen on the surface of their red blood cells, and the anti-B antibody in their blood serum.
from A to Z
(click for a larger image)Marquee, Radio City Music Hall
Opened in 1932, Radio City Music Hall is a landmark in New York's Rockefeller Center.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.