Listed in the "Curses" section of the KCD Language Lab. In TOS "The Trouble with Tribbles", this was an insult aimed at Kirk by Lt. Korax with the implication that he was spineless and weak. It's also called a {DenIbya' Qatlh}.
The "soft and shapeless" insult was a *Regulan bloodworm*. Calling him a Denebian slime devil was an additional insult, without further explanation.