Low-complexity just intonation

Low-complexity just intonation (LCJI, low JI or simple JI) is a term often used for a style of just intonation (JI) that is based on a restricted set of simple JI intervals (such as 3/2, 4/3, 5/4, 6/5, 7/4, 7/6, 9/8, 11/8, 13/8, 15/8); higher complexity ratios may be generated by such a set, but are not used directly and are only reached by modulating away from the original key. There is no universal boundary for LCJI, but the 15-odd-limit is a good candidate.

Terminology

This term is coined by Zhea Erose, who uses it in opposition to higher-harmonic-series JI approaches such as primodality, nejis, and higher harmonic tuning. Low JI is sometimes seen in the community. Meanwhile, Flora Canou proposes simple JI for a connotation-neutral variant.