member of the guitar family

The ukulele (pronounced /ˌjʉːkəˈlɛɪli/ from the Hawaiian ʻukulele, pronounced /ˈʔukuˈlɛlɛ/) is a musical instrument with four strings. It is also called the uke for short. Ukuleles are part of the guitar family of instruments. The strings are usually tuned G, C, E, A' or A, D, F#, B. Ukuleles normally have nylon strings or gut strings.

String instrument
Classification String instrument (plucked, nylon stringed instrument usually played with the bare thumb and/or fingertips, or a felt pick.)
Related instruments

Ukuleles commonly come in four sizes: soprano, concert, tenor and baritone. Sopranino and bass ukuleles also exist. Sopraninos are tuned to standard tuning, however, baritone ukuleles are tuned to D, G, B, E (the top four strings of a guitar). Bass ukuleles are tuned E, A, D, G (bass guitar and double bass tuning).

The ukulele was invented in the 19th Century in Hawaii, where people got the idea from small guitar-like instruments known as cavaquinhos brought to the island by Portuguese sailors.