I'm confused about the differing pronunciations of words that end in "-b". For example, I remember being told by some of earliest teachers that the "-b" in limb was meant to be silent, and one should properly pronounce it as lim.

Now, that seems to me in contrast with the pronunciation of the word thumb, which I find, verifying through an impromptu poll of friends just now, is often pronounced with the enunciated "-b". If that weren't confusing enough, think of the pronunciation of the word crumb; the enunciation of the final b seems clearly wrong to my ear. But the verb and the participle made out of the noun clearly have their "-b"s enunciated; think crumbled and crumbling.

So I guess my question is: What exactly are the rules here? Which pronunciation is more faithful to the etymology of these words?

  • 4
    I pronounce the b in limbic, Thumbelina, and crumble. I used to keep silent about that, but not anymore.
    – Robusto
    Commented May 17, 2011 at 1:45
  • 1
    Where are you, Uticensis: I wonder if some people in the North West pronounce the final /b/ in the same way that they pronounce a final /g/ on words like "sing"?
    – Colin Fine
    Commented Dec 23, 2013 at 17:57
  • 2
    What does your dictionary say?
    – rogermue
    Commented May 1, 2014 at 10:34

3 Answers 3


All of the words you provide (limb, thumb, crumb) are listed in my local dictionary without a b sound. Things seem basically the same with suffixes (i.e. thumbed has no b sound).

Crumbled is is a completely different word and receives the pronunciation typical for "mble": thimble, tremble, fumble, etc.

It is true that crumb and crumble have common origins:

crumb - O.E. cruma "crumb, fragment," from a W.Gmc. root of obscure origin (cf. M.Du. crume, Du. kruim, Ger. krume).

crumble - late 15c., kremelen, from O.E. _*crymelan_, presumed frequentative of gecrymman "to break into crumbs," from cruma (see crumb).

The "b" in each word appeared later (mid-15c for crumb and 16c for crumble). Given the typical pronunciation of the "mb" and "mble" it isn't surprising that these words are treated the same. Why they received a "b" at all is a little vague from the notes in the above link.

Digging deeper I found Anatoly Liberman who gave a more thorough explanation:

The words thumb, numb, and dumb have unetymological mb in spelling, though they do not end in l. Why do they? In principle, the story begins in late Middle English. At that time, consonantal groups were often simplified. Solemn and column are now pronounced without n. In the speech of some people kiln is homophonous with kill, g is always mute in diaphragm, phlegm, and so forth. Because of the simplification, lamb was fleeced of its historical final b; today b is retained in spelling but not in pronunciation. The same happened to jamb, plumb, and tomb (borrowed words), along with womb (Old Engl. wamba “belly”; compare Wamba, the name of Cedric’s “fool” in Ivanhoe) and climb (Old Engl. climban).

As long as the simplification of consonantal groups remained an active force, literate people felt uncertain when to write m, as opposed to mb, and began to add b to m gratuitously, a mistake (here, reverse spelling) called hypercorrection. This accounts for the modern forms limb and crumb.

The rest of that article is extremely fascinating and highly recommended. Also relevant are words like limber, timber, combine which most certainly pronounce the b despite the "mb". So are other cases of a silent "b": debt, subtle, etc.

  • +1 Nice job. I didn't see this before, and was wondering just this morning about the silent b at the ends of such words.
    – Robusto
    Commented Feb 11, 2012 at 15:11
  • the rules are: don't pronounce the 'b' in any of the root words limb crumb dumb lamb thumb (just check an online dictionary). That is, your friends may be reporting that they're pronouncing the b, but they most likely are not (or if they are they are being influenced by the question).
  • for some derived words, you may or may not pronounce the 'b': crummy, dummy, but limbic (the b is pronounced in the latter).
  • as to "Which pronunciation is more faithful to the etymology of these words?", being faithful to the etymology would result in incomprehension for most English words, e.g. 'night'

There is no word in the English that ends in -mb where the b is pronounced. It is always silent in that position, just like the way the k is always silent in words beginning with kn-.

Examples include, but are not limited to, the following:

  • aplomb
  • bomb
  • catacomb
  • choriamb
  • climb
  • comb
  • crumb
  • dumb
  • lamb
  • limb
  • numb
  • plumb
  • succumb
  • thumb
  • tomb
  • womb

Indeed, a native speaker will have considerable difficulty rendering any of those in a way that does have a /b/ at the end.

  • 1
    I pronounce iamb and choriamb with their final b, and so does the OED.
    – fdb
    Commented May 1, 2014 at 8:07

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