A
In physics, symbol for ampere, a unit of electrical current.
A
| First letter in the English alphabet and nearly all others. The letter is derived from the Etruscan a, via the Latin alphabet, the parent of the Western European alphabets. The first letter in the Greek alphabet was called alpha (Α, α); it was called aleph or alph in the Semitic, meaning ‘ox’, probably because the word began with this sound. |
A
The note A in the treble clef.
| In music, the first note of the diatonic scale A–G, or A above middle C; orchestral concert pitch. |
a
| In English grammar, the indefinite article. |
A
| Symbol for mass number, the number of neutrons and protons in an atomic nucleus. |
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