imperfecto.

(a loanword from Spanish)

Headword: 
imperfecto.
Principal English Translation: 

imperfect; can have a musical referent (see attestations)

Attestations from sources in Spanish: 

Quinto tono inperfecto quituznequi amo cenquizqui = Quinto tono imperfecto quiere decir que no es completo. (seventeenth-century Guatemala)
Fernando Horcasitas y Alfred Lemmon, "El Tratado de Santa Eulalia: un manuscrito musical náhuatl," Tlalocan 12 (1997), 96–97.