Noun

1. Any abrupt and inexplicable transition or occurrence.

   Having a costumed superhero abduct the vicar was an utter non sequitur in the novel.

2. Any invalid argument in which the conclusion cannot be logically deduced from the premises; a logical fallacy.
3. A kind of pun that uses a change of word, subject, or meaning to make a joke of the listener’s expectation.

Usage notes

• Other pluralizations are non sequituri (which is not proper Latin) and non sequiuntur (which is proper Latin, but conveys a possibly ambiguous meaning: ); both are neologistic folk etymology. As non sequitur is a phrase, rather than a noun in Latin, its borrowing into English as a noun requires regular English plural formation, ergo non sequiturs.

See also

• deus ex machina
• fallacy
• paradox
• Wikipedia article on logical fallacy
• Wikipedia article on non sequiturs
• List of types of logical fallacy