Definition of "ouch"

ouch¹

/ˈaʊt͡ʃ/

interjection
1. An expression of one's own physical pain.
2. An expression in sympathy at another's pain.
3. A reply to an insult seen as savage (frequently one that is tongue-in-cheek or joking).
4. An expression of disappointment.
5. (slang) Expressing surprise at the high price of something.
noun
plural ouches
1. (informal) Something that causes discomfort or pain.
  Quotations
  RhuliGel soothes the itches and ouches of summer.
  1986 June, “RhuliGel Soothes the Itches and Ouches of Summer [advertisement]”, in Myrna Blyth, editor, Ladies’ Home Journal, volume CIII, number 6, New York, N.Y.: Meredith Publications, page 161, column 2
verb
third-person singular simple present ouches, present participle ouching, simple past and past participle ouched
1. (intransitive) To exclaim "ouch!" in discomfort or pain.
  Quotations
  Imperturbability your skill, not mine / I ouch out loud and clear / Your forgiveness, like Pope's divine / I'm just an angry queer
  1984 April 21, “Mousie Mousie Wildflower”, in Gay Community News, page 18

ouch²

noun
plural ouches
1. Alternative form of ouche