from The American Heritage® Dictionary of the English Language, 5th Edition.

  • adjective Inducing or tending to induce sleep.
  • adjective Drowsy.
  • noun A drug or other substance that induces sleep; a hypnotic.

from The Century Dictionary.

  • Tending to produce sleep.
  • noun Anything which causes sleep, as certain medicines.

from the GNU version of the Collaborative International Dictionary of English.

  • adjective Causing sleep; tending to cause sleep; soporiferous.
  • noun A medicine, drug, plant, or other agent that has the quality of inducing sleep; a narcotic.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun Something inducing sleep, especially a drug.
  • noun figuratively Something boring or dull.
  • adjective Tending to induce sleep.
  • adjective figuratively boring, dull

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adjective inducing mental lethargy
  • noun a drug that induces sleep
  • adjective sleep inducing


from Wiktionary, Creative Commons Attribution/Share-Alike License

From French soporifique, from Latin sopor ("deep sleep"), from Proto-Indo-European *swepōr, from Proto-Indo-European *swep-. Unrelated to stupor (distinct in Proto-Indo-European).


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  • "It is said that the effect of eating too much lettuce is 'soporific.'

    "I have never felt sleepy after eating lettuces; but then I am not a rabbit.

    "They certainly had a very soporific effect upon the Flopsy Bunnies!"

    -Beatrix Potter, The Tale of the Flopsy Bunnies.

    December 12, 2006

  • 1. a. causing or tending to cause sleep. b. tending to dull awareness or alertness.

    2. of, relating to, or marked by sleepiness or lethargy

    December 11, 2007

  • I always bring out the Beatrix Potter quote as evidence that it is possible to nurture wordie-ness even in the very young. This is one of the very earliest books I remember reading. And even then I "got" what she was trying to do to my vocabulary, and I've been using the word ever since.

    March 31, 2008

  • Beatrix Potter's use of soporific is also invoked in Margaret Edson's excellent play W;t. (Also a film, the clever typography is meant to come out as Wit.)

    March 31, 2008

  • Soporific means causing sleepiness. Something is soporific if it causes sleepiness. If the effect of something is sleepiness, that thing is soporific. It is not the effect of that thing that is soporific, it is the thing itself, which is a cause.

    Lettuce is soporific: the effect of eating lettuce is sleepiness. It is the cause of sleepiness--the lettuce--that is soporific, not the effect of that cause. It is possible that sleepiness is soporific (in that it tends to cause more sleepiness), but Beatrix Potter wanted to communicate the idea that lettuce itself causes sleepiness, not that sleepiness causes sleepiness.

    She apparently had a desire to introduce the word "soporific", but she did so inaptly. Instead of saying, "It is said that the effect of eating too much lettuce is soporific," she should have said, "It is said lettuce is soporific, that eating too much lettuce makes you sleepy."

    March 17, 2009

  • Wait, eating lettuce makes you sleepy?

    March 30, 2009

  • Beddy bye-byes, bun-bun.

    March 30, 2009

  • The first pages, of most of these old papers, are as soporific as a bed of poppies.

    Nathaniel Hawthorne, Tales and Sketches

    November 23, 2011

  • adjective: inducing mental lethargy; sleep inducing

    Although the professor is brilliant, his bland monotone gives his lectures a soporific effect.

    October 19, 2016