nybble /nib'l/ (alt. `nibble') n.
[from v. `nibble' by analogy with `bite' => `byte'] Four bits; one hex digit; a half-byte. Though `byte' is now techspeak, this useful relative is still jargon. Compare byte; see also bit. The more mundane spelling "nibble" is also commonly used. Apparently the `nybble' spelling is uncommon in Commonwealth Hackish, as British orthography would suggest the pronunciation /ni:'bl/.