Noun

1. Letters or words, in writing or speech, that have no meaning or seem to have no meaning.
2. An untrue statement.

   He says that I stole his computer, but that's just nonsense.

3. Something foolish.
   • 2008, "Nick Leeson has some lessons for this collapse", Telegraph.co.uk, Oct 9, 2008

     and central banks lend vast sums against marshmallow backed securities, or other nonsenses creative bankers dreamed up.

4. A type of poetry that contains strange or surreal ideas, as, for example, that written by Edward Lear.
5. A damaged DNA sequence whose products are not biologically active, that is, that does nothing.

Synonyms

See WikiSaurus:nonsense

• • balderdash, baloney, bull, bulldust, bunk, codswallop, drivel, gibberish, hogwash, hooey , horse hockey, malarkey, manure, poppycock, prattle, rhubarb , rubbish, twaddle
  • bollocks , bullshit, crap, horseshit

Verb

1. To make nonsense of
   • , Bernard Shaw, "The Red Robe", in James Huneker ed., Dramatic Opinions and Essays by G. Bernard Shaw, volume II, page 73:

     At the Haymarket all this is nonsensed by an endeavor to steer between Mr. Stanley Weyman's rights as author of the story and the prescriptive right of the leading actor to fight popularly and heroically against heavy odds.

2. To attempt to dismiss as nonsense.
   • 1997, "Rockies respond to whip", Denver Post, Jun 3, 1997:

     "They haven't nonsensed these workouts. They've taken them and used them very well. I didn't know how they'd respond, but they've responded."

   • 2000, Leon Garfield, Jason Cockcroft, Jack Holborn, page 131:

     Very commanding: very much 'end of this nonsensing'. Mister Fared spread his hands and shook his thin head imperceptibly, as if to say he understood

   • 2006, Sierra Leone: Petroleum Unit Calls for Auditing, AllAfrica.com, Mar 17, 2006:

     He further nonsensed press suggestions that the Petroleum Unit was set up to assist in the administration of sporting activities.

3. To joke around, to waste time
   • 1963, C. F. Griffin, The Impermanence of Heroes, page 170:

     When he meant "go and get one" he said to go and get one, with no nonsensing around about "liking" to get one.