A new financial company launched its plans to "increase the liquidity of NFTs" this week, announcing its name: "Nonce Finance will launch itself on Polygon!" A nonce is a code used only once, and in this sense is of particular utility to cryptography, the discipline in which NFTs are grounded. But outside these circles, the term nonce is more commonly used as slang for those convicted of sexual assaults on children.
Several origins have been proposed; possibly derived from dialectal nonce, nonse ("stupid, worthless individual") (but this cannot be shown to predate nonce "child-molester" and is likely a toned-down usage of the same insult), or Nance, nance ("effeminate man, homosexual"), from nancy or nancyboy. The rhyme with ponce has also been noted.
As prison slang also said to be an acronym for "Not On Normal Communal Exercise" (Stevens 2012), but this is likely a backronym.
Oh dear. Here's one well-known use of the term, from "Paedogeddon", Brass Eye's darkly humorous 2001 episide about the way UK media whips up sensationalist hysteria about pedophilia while avoiding any substantive discussion of child sexual abusers. Pop star Phil Collins has been fooled by producers into wearing a t-shirt emblazoned with a fake antipedophilia slogan, "NONCE SENSE".
The less pleasant meaning is present in most dictionaries and there are no excuses.