Well for one thing, it’s an instrument, but I guess that’s fairly easily deduced, isn’t it? However, it can be supposed that lyre was once used, or may still be today as a catch all general term for “harp”, though a harp is often much larger. If there ever was a formula for what a lyre actually was, it always depended on where it was made, since so many cultures, all over the world, have their own forms of the instrument. It is depicted commonly in art, mostly European, played by the angels, nymphs, fairies, goddesses, –almost always by divine entities, or mortals with connections to a divine spirit of one kind or another.
The lyre is usually portrayed as being strummed with a plectrum, (a bit like a guitar pick in function) more like a guitar,or zither, which leads us away from the confusion of generalising it as a type of harp, which is plucked with the fingers. Using one’s free hand, the player would rest it against the strings of the lyre to silence the unwanted chords. The prayers, or recitations, chanting, rituals, and ceremonies of Ancient Greeks were often accompanied with the sound of the lyre’s music, which is probably where Classic Greek Antiquity got so much art that featured the lyre player, since it was imbued with sacred religious meaning.
Musical experts attempting to classify the lyre usually run into trouble when trying to label the instrument. Mostly, however, it is put into the “zither class” of stringed instruments, because, –it has strings. However, other experts argue, because the lyre has no backboard, like a harp, and instead, put it inside the lute class, with other instruments that are strummed, rather than plucked at. The number of strings, and the instrument’s size have nothing to do with its classification, however, it also doesn’t fit into the harp category, because of its dimensions and sound. Personally, it deserves a class of its own, in my opinion, so as to stop all the confusion.