Source : Webster's Revised Unabridged Dictionary (1913)

Nibble \Nib"ble\, v. t.
   To bite upon something gently or cautiously; to eat a little
   of a thing, as by taking small bits cautiously; as, fishes
   nibble at the bait.

         Instead of returning a full answer to my book, he
         manifestly falls a-nibbling at one single passage.
                                                  --Tillotson.

Nibble \Nib"ble\, n.
   A small or cautious bite.

Nibble \Nib"ble\, v. t. [imp. & p. p. {Nibbled}; p. pr. & vb. n.
   {Nibbling}.] [Cf. {Nip}.]
   To bite by little at a time; to seize gently with the mouth;
   to eat slowly or in small bits.

         Thy turfy mountains, where live nibbling sheep. --Shak.

Source : WordNet®

nibble
     v 1: bite off very small pieces; "She nibbled on her cracker"
     2: bite gently; "The woman tenderly nibbled at her baby's ear"
     3: eat intermittently; take small bites of; "He pieced at the
        sandwich all morning"; "She never eats a full meal--she
        just nibbles" [syn: {pick}, {piece}]

nibble
     n 1: a small byte [syn: {nybble}]
     2: gentle biting

Source : Free On-Line Dictionary of Computing

nibble
     
         /nib'l/ (US "nybble", by analogy with "bite" -> "byte")
        Half a {byte}.  Since a byte is nearly always eight {bits}, a
        nibble is nearly always four bits (and can therefore be
        represented by one {hex} digit).
     
        Other size nibbles have existed, for example the {BBC
        Microcomputer} disk file system used eleven bit sector numbers
        which were described as one byte (eight bits) and a nibble
        (three bits).
     
        Compare {crumb}, {tayste}, {dynner}; see also {bit}, {nickle},
        {deckle}.
     
        The spelling "nybble" is uncommon in {Commonwealth Hackish} as
        British orthography suggests the pronunciation /ni:'bl/.
     
        (1997-12-03)