from
The Collaborative International Dictionary of English v.0.48
Coin \Coin\ (koin), n. [F. coin, formerly also coing, wedge,
stamp, corner, fr. L. cuneus wedge; prob. akin to E. cone,
hone. See {Hone}, n., and cf. {Coigne}, {Quoin},
{Cuneiform}.]
1. A quoin; a corner or external angle; a wedge. See
{Coigne}, and {Quoin}.
[1913 Webster]
2. A piece of metal on which certain characters are stamped
by government authority, making it legally current as
money; -- much used in a collective sense.
[1913 Webster]
It is alleged that it [a subsidy] exceeded all the
current coin of the realm. --Hallam.
[1913 Webster]
3. That which serves for payment or recompense.
[1913 Webster]
The loss of present advantage to flesh and blood is
repaid in a nobler coin. --Hammond.
[1913 Webster]
{Coin balance}. See Illust. of {Balance}.
{To pay one in his own coin}, to return to one the same kind
of injury or ill treatment as has been received from him.
[Colloq.]
[1913 Webster]