I expect someone lives there in secret, only coming in and out at night, with a dark lantern. We shall probably discover a gang of desperate criminals and get a reward. It's all rot to say a house would be empty all those years unless there was some mystery.

rot verb /rɒt//rɑːt/ [I or T] (-tt-) Definition: to (cause to) decay
  The fruit had been left to rot on the trees.
  Rain has got in and rotted (away) the woodwork.
  the smell of rotting fruit

Doesn't make sense.

3 Answers 3


Rot in this context is a noun which means "nonsense." In that sentence, "all rot" could probably be replaced by ridiculous or absurd and still mean generally the same thing.

  • 5
    I think of "It's all rot" as a particularly British expression.
    – Kit Z. Fox
    Jun 23, 2011 at 18:05
  • Think of the implications of rot: "falls apart easily," "smells bad," "not useful'
    – horatio
    Jun 23, 2011 at 18:18
  • 1
    we used to say "all rot" = "rubbish" for the same reasons as horatio has put
    – JoseK
    Jun 23, 2011 at 18:20
  • @KitFox. British. Upper-middle-class. Seen most often in children's detective fiction of a certain vintage. The phrase it's all rot immediately makes me think of Enid Blyton.
    – TRiG
    Apr 6, 2012 at 13:33
  • @KitZ.Fox -- Certainly "rot", in this sense, is well-known in the US.
    – Hot Licks
    Nov 26, 2015 at 22:37

It is a common enough idiom in Britain so that C. S. Lewis, whom you quote, wouldn't have thought twice about using it. One must think of idioms metaphorically, because literally, as you correctly observe, they don't "make sense." If something has some rot, it is partially usable, if it is "all rot," then no part of it is salvageable and it should all be thrown away. In this case, "all rot" means there is not a shred of truth in the statement.


Don't take it so literally. "Rot" in this context means "rubbish" or "B.S.", "garbage", or simply "nonsense". Other terms with the same meaning are: baloney, bosh, balderdash, bunk, eyewash, hogwash, hooey, poppycock, tommyrot, trash, twaddle, tripe, etc.

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