preantepenultimate
/ˌpriːˌantɪpɪˈnʌltɪmət/Chiefly Phonetics
adjective
That precedes or stands immediately before the antepenult; the last but three.
Origin
Mid 18th century (in an earlier sense). As noun from pre- + antepenultimate. As adjective from pre- + antepenultimate.