TRES:
Stringed instrument
native to Cuba. A cousin of the guitar, from
which
it is derived. Composed of three doubled sets of steel strings
over a
wooden neck and soundbox, with one set tuned in unison and the other
two in octaves. Usually played with a pick made of tortoise-shell
or plastic.
Its fundamental use is in Cuban son and punto guajiro groups. (from "Diccionario de
la Musica Cubana," by Helio Orovio)