Law To punish by a fine imposed arbitrarily at the discretion of the court.
To punish by imposing an arbitrary penalty.
[Middle English amercen, from Anglo-Norman amercier, from à merci, at the mercy of : à, to (from Latin ad; see ad-) + merci, mercy (from Latin mercēs, wages).] a·merce'a·ble adj., a·merce'ment n.