A string that is not pressed with the finger of the fret hand, but vibrates freely. The resulting tone corresponds to the tuning of this string; thus, A for the A-string, E for the E-string etc.

Open Chords on the Ukulele

In the open basic position (every string is open = no string is plucked) of a tuned Ukulele the following sounds are heard:

tuning
StringC6D6Es6G6Interval on root note
1ABCEsixth
2EF#GBMajor third
3CDEbG
4GABbDfifth

Thus, the open chords on the ukulele are a third-fifth chord (= major chord) with additional sixths (hence, depending on the chord root, called C6, D6 or G6; see sixth chord).