於

wū
  1. (literary) Oh!
  2. Ah!

CEDICT

literary

Homographs

於 yú
  1. (of time or place) in; at; on
  2. (indicating any indirect relation) to; toward; vis-à-vis; with regard to; for
  3. (indicating a source) from; out of
  4. (used in comparison) than
  5. (used in the passive voice) by
於 Yū
  1. surname Yu
  2. Taiwan pr. Yú