A low-register 6-string instrument in the guitar family, tuned BEADGC an octave below standard tuning, often (but not always) with a solid wooden body. The classical contrabass guitar is tuned EADGBE, like the classical guitar but one octave lower.

It is popular in Fado bands in Portugal and South America. In this sense, it may actually can be considered as an acoustic bass guitar, for it shares the same low-end range.