nonce

noun

1. (archaic)The one or single occasion; the present reason or purpose.

   “That will do for the nonce, but we'll need a better answer for the long term.”

   “[...] Dunce, / Dotard, a-dozing at the very nonce, / After a life spent training for the sight!”

   “'Idiot!' exclaimed the doctor, who for the nonce was not capable of more than such spasmodic attempts at utterance.”

2. A nonce word.

   “I had thought that the term was a nonce, but it seems as if it's been picked up by other authors.”

3. A value constructed so as to be unique to a particular message in a stream, in order to prevent replay attacks.

   “The protocol opens with A communicating in clear to AS his own claimed identity and the identity of the desired correspondent, B, together with A's nonce identifier for this transaction, I_(A1). ("Nonce" means "used only once.")”

   “The information gained by the eavesdropper would permit a replay attack, but only with a request for the same document, and even that may be limited by the server's choice of nonce.”

   “Both CCM and GCM require a unique nonce (N used once) value to maintain their privacy and authenticity goals.”

   “The main idea with the challenge-response type of authentication protocol is that the challenge sent by the server is used only once (referred to as a cryptographic nonce, which means “number used once”).”

4. (British, Ireland, derogatory)A sex offender, especially one who is guilty of sexual offences against children.

   “1989 "assorted nonces, ponces and murderers, 'the worst men in the world' … on the nonce wing, where the child-killers, molesters and various perverts have to be protected from the other prisoners." (New Statesman, New Society, Volume 2, Statesman & Nation Publishing Company Limited)”

5. (broadly)A pedophile.

   “‘He's a nonce[. A] nonsense merchant, a paedophile[,’ Terry explained.]”

6. (British, Ireland, derogatory, slang)A police informer, one who betrays a criminal enterprise
7. (British, Ireland, derogatory, slang)A stupid or worthless person.

   “Shut it, ya nonce!”

adj

1. (not-comparable)One-off; produced or created for a single occasion or use. Denoting something occurring once.

   “But particular men are not stereotyped for jobs nor particular desks (as against others) to sit at - the standard here is nonce.”

   “Dickinson's association of heliotrope with Mary Bowles was nonce and fleeting, but the subject of gardens was always a safe one on which to address her: “How is your garden – Mary? Are the Pinks true –?””

   “Poplack et al. (1988, 57) found that 65% of their types were nonce and only 7% of the types were considered widespread.”

   “Some of the single-citation terms appeared to be nonce formations, that is, created for the occasion.”