おし

  1. noun (common) (futsuumeishi), nouns which may take the genitive case particle 'no', noun, used as a suffix

    being a fan of, being a supporter of, pushing for
    colloquial

  2. noun (common) (futsuumeishi)

    one's favourite (member of an idol group, character in an anime, player in a team, etc.)
    slang