What is the meaning of Oof?

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

Synonym of ouch (expressing sympathy at another's pain, shock at a high price, etc.)

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

Something cringeworthy, or which arouses disappointment, often used in conjunction with the qualifier big.

Money.

to have sex

Source: wiktionary.org