The Collaborative International Dictionary of English v.0.48:

Crumb \Crumb\ (kr[u^]m), n. [AS. cruma, akin to D. kruim, G.
   krume; cf. G. krauen to scratch, claw.] [Written also
   crum.]
   1. A small fragment or piece; especially, a small piece of
      bread or other food, broken or cut off.
      [1913 Webster]

            Desiring to be fed with the crumbs which fell from
            the rich man's table.                 --Luke xvi.
                                                  21.
      [1913 Webster]

   2. Fig.: A little; a bit; as, a crumb of comfort.
      [1913 Webster]

   3. The soft part of bread.
      [1913 Webster]

            Dust unto dust, what must be, must;
            If you can't get crumb, you'd best eat crust. --Old
                                                  Song.
      [1913 Webster]

   Crumb brush, a brush for sweeping crumbs from a table.

   To a crum, with great exactness; completely.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Crumb \Crumb\, v. t. [imp. & p. p. Crumbed (kr[u^]md); p. pr.
   & vb. n. Crumbing (kr[u^]m"[i^]ng).]
   To break into crumbs or small pieces with the fingers; as, to
   crumb bread. [Written also crum.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

crumb
    n 1: a very small quantity of something; "he gave only a crumb
         of information about his plans"; "there were few crumbs of
         comfort in the report"
    2: a person who is deemed to be despicable or contemptible;
       "only a rotter would do that"; "kill the rat"; "throw the bum
       out"; "you cowardly little pukes!"; "the British call a
       contemptible person a `git'" [syn: rotter, dirty dog,
       rat, skunk, stinker, stinkpot, bum, puke,
       crumb, lowlife, scum bag, so-and-so, git]
    3: small piece of e.g. bread or cake
    v 1: coat with bread crumbs; "crumb a cutlet"
    2: break into crumbs
    3: remove crumbs from; "crumb the table"

The Free On-line Dictionary of Computing (19 January 2023):

crumb
quarter
tayste

    (Or tayste /tayst/) Silly suggested term for
   two binary digits.

   The term "quarter" has also been suggested, referring to the
   US 25-cent coin.  This was once equal in value to two of the
   eight "bits" - pie-slice-shaped "pieces of eight" - into which
   Spanish silver crowns were cut to make change.

   [Jargon File]

   (2007-05-31)


The Jargon File (version 4.4.7, 29 Dec 2003):

crumb
 n.

    Two binary digits; a quad. Larger than a bit, smaller than a nybble.
    Considered silly. Syn. tayste. General discussion of such terms is under
    nybble.