-으이-

• 이 (-i-) – after vowels and ㄹ (l)

From Middle Korean -으〮ᅌᅵ/ᄋᆞ〮ᅌᅵ- (Yale: -úngì/óngì-, addressee-honoring suffix).

으이 • (-eu'i-)

1. (Early Modern or Gyeongsang) A suffix adding an intensified degree of politeness or deference.

   아부지, 떡 좀 잡수이소. (Gyeongsang dialect, Changwon)

   Abuji, tteok jom japsu-i-so.

   Father, have some rice cakes.

• In contemporary Gyeongsang, it attaches only to 소 (-so) and 읍시다 (-eupsida), the imperative and hortative suffixes of the semi-formal style respectively, to form 으이소 (-eu'iso) and 으입시다 (-eu'ipsida), the imperative and hortative moods of the formal polite style respectively.
• The formal polite style is less formal in Gyeongsang than in contemporary Seoul Korean, and hence can be used by e.g. a child addressing one's parents. In these contexts, it coexists with the polite style formed by 예 (-ye).
• This suffix is not used in northwestern Gyeongsang (e.g. Andong).