aesthetic, cathartic, or erotic suffering in fiction.

from fanlore–

The term whump (or whumping) generally refers to a form of Hurt/Comfort that is heavy on the hurt and is often found in gen stories. The exact definition varies and has evolved over time. Essentially, whump involves taking a canon character, and placing them in physically painful or psychologically-damaging scenarios. Often this character is a fan favorite and may sometimes be referred to as a woobie.

Whump, as a term, is believed to have originated in the Stargate SG-1 fandom. OXBastedXO, a FFN user states in her profile that one of her minor claims to fame is coining the term Danny Whumping in the fandom.[note 1] However, another fan claims: “I saw it used in 1996, in the Earth 2 fandom,” which would suggest the term predates even the Stargate SG-1 fandom.[2]