The cavaco, more commonly known has the cavaquinho, is a Portuguese musical instrument resembling a small guitar with four steel strings. The sound of the instrument is high-pitched and loud. Used first in Portuguese traditional music, it became an important instrument in Brazilian music, especially samba and choro. The standard tuning is D-G-B-D. Some of the most important players and composers in the instrument's Brazilian incarnation are Waldir Azevedo and Paulinho da Viola .

As early as 1879, Portuguese immigrants brought cavacos (which were then called braguinhas) to Hawaii, and there a local variant (with less tension and a correspondingly quieter sound) became known as the ukulele.