Webster's 1828 Dictionary
TESTOON
n.A silver coin in Italy and Portugal. In Florence, the testoon is worth two lire or three paoli, about seventeen pence sterling, or thirty two cents. At Lisbon, the testoon, as a money of account, is valued at 1 rees, about seven pence sterling, or twelve and a half cents.
Webster's 1913 Dictionary
TESTOON
Tes *toon ", n. Etym: [It. testone. See Tester a coin. ]
Defn: An Italian silver coin. The testoon of Rome is worth 1s. 3d. sterling, or about thirty cents. Homans.