- Noun. The one or single occasion; the present reason or purpose (now only in ''for the nonce'').
- Noun. (lexicography) A nonce word.
- Noun. (computing) A number, usually generated randomly or from the time, used once in a cryptographic protocol, to prevent replay attacks.
- Adjective. denoting something occurring once. .
- Noun. (British, slang) A sex offender, ''especially'' of children; a paedophile.
- Noun. (British, slang) A stupid or worthless person.
- Noun. (cryptography) A datum constructed so as to be unique to a particular message in a stream, in order to prevent replay attacks.
- Noun. (cryptography) In a security engineering context, a value used only once.