Tuning of a stringed instrument where not all strings are not arranged in the ascending (or descending) order of the scale but where at least one of the strings returns to a preceding note.

Traditionally, Ukuleles have reentrant tuning, meaning that the 4^th string is tuned higher than the 3^rd, whereas in non-reentrant = linear tuning, the 4^th string is lower than the 3^rd.