nonce

1. The one or single occasion; the present reason or purpose (now only in for the nonce).

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

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.

adjective

One-off; produced or created for a single occasion or use. Denoting something occurring once.

1. (prisons) 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)

2. (prisons) A police informer, one who betrays a criminal enterprise
3. A stupid or worthless person.

   Shut it, ya nonce!