Definition of o-omi in US English:

o-omi

(also o-mi)

noun

historical
  • In early imperial Japan: the leader of all the heads clans or families claiming imperial ancestry (see omi, who served as the highest minister in the Yamato court until the Taika reform (646).

Origin

Early 20th century; earliest use found in Frank Brinkley (1841–1912). From Japanese ō-omi from ō- great + omi.