A [among the Ancients]

A [among the Ancients]
was a numeral Letter, and signified 500.

Definition taken from The Universal Etymological English Dictionary, edited by Nathan Bailey (1736)

A * Ā, or ā
A
A [among the Ancients]
Ā, or ā
A [among the Romans]
Abeˊston
Absoˊrb [with Gardeners, &c.]
Absorb
Absoˊrbents
Actinoˊbolism
Aˊction
Action [in Physics]
Spontaneous Action [with Philosophers and Physicians]