in antiquity, a very small brass coin in use among the Romans.

The inconvenience of such very small pieces being soon found, the teruncius became disused, but its name is still retained in reckoning, and thus it became a money of account. The teruncius at first was a quarter of the as, or libra; hence, as the as contained twelve asses, the teruncius contained three, whence the name, which is formed of the Latin tres unciae. Teruncius was also used for the quarter of the denarii; so that when the denarius was at ten asses, the teruncius was worth two and a half; and when the denarius was risen to sixteen, the teruncius was worth four. See Denarius.