The Collaborative International Dictionary
Phorminx \Phor"minx\, n. [NL., fr. Gr. ?.]
A kind of lyre used by the Greeks.
--Mrs. Browning.
Wiktionary
n. A kind of lyre used by the Ancient Greeks.
Wikipedia
The phorminx (in Ancient Greek φόρμιγξ) was one of the oldest of the Ancient Greek stringed musical instruments, intermediate between the lyre and the kithara. It consisted of two to seven strings, richly decorated arms and a crescent-shaped sound box. It mostly probably originated from Mesopotamia. While it seems to have been common in Homer's day, accompanying the rhapsodes, it was supplanted in historical times by the seven-stringed kithara. Nevertheless, the term phorminx continued to be used as an archaism in poetry.
The term phorminx is also sometimes used in both ancient and modern writing to refer to all four instruments of the lyre family collectively:
Usage examples of "phorminx".
In the oldest times, those of Homer and Hesiod, it was called phorminx, which is believed to have been the form so often represented on Greek vases of a turtle shell with side pieces like horns, an instrument having but little effective resonance.