OOF

noun

1. A sound made in pain, as when expelling air after being struck.

interjection

1. A sound mimicking the loss of air, as if someone's solar plexus had just been struck.

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).