The Collaborative International Dictionary of English v.0.48:

Twiddle \Twid"dle\, v. t. [Probably of imitative origin. Cf.
   Tweedle.]
   To touch lightly, or play with; to tweedle; to twirl; as, to
   twiddle one's thumbs; to twiddle a watch key. [Written also
   twidle.] --Thackeray.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Twiddle \Twid"dle\, v. i.
   To play with anything; hence, to be busy about trifles.
   --Halliwell.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Twiddle \Twid"dle\, n.
   1. A slight twist with the fingers.
      [1913 Webster]

   2. A pimple. [Prov. Eng.] --Halliwell.
      [1913 Webster]

WordNet (r) 3.0 (2006):

twiddle
    n 1: a series of small (usually idle) twists or turns
    v 1: turn in a twisting or spinning motion; "The leaves swirled
         in the autumn wind" [syn: twirl, swirl, twiddle,
         whirl]
    2: manipulate, as in a nervous or unconscious manner; "He
       twiddled his thumbs while waiting for the interview" [syn:
       twiddle, fiddle with]

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

twiddle

   1.  The tilde character.

   2.  (To make) a small or insignificant change.
   E.g. twiddling a program often fixes one bug and generates
   several new ones (see also shotgun debugging).  Bits are
   often twiddled.  Twiddling a switch or knob implies much less
   sense of purpose than toggling or tweaking it; see
   frobnicate.  Bit twiddling connotes aimlessness, and at
   best doesn't specify what you're doing to the bit; to
   "toggle a bit" has a more specific meaning.

   [Jargon File]

   (1995-01-31)


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

twiddle
 n.

    1. Tilde (ASCII 1111110, ~). Also called squiggle, sqiggle (sic —
    pronounced /skig'l/), and twaddle, but twiddle is the most common term.

    2. A small and insignificant change to a program. Usually fixes one bug and
    generates several new ones (see also shotgun debugging).

    3. vt. To change something in a small way. Bits, for example, are often
    twiddled. Twiddling a switch or knobs implies much less sense of purpose
    than toggling or tweaking it; see frobnicate. To speak of twiddling a bit
    connotes aimlessness, and at best doesn't specify what you're doing to the
    bit; ‘toggling a bit’ has a more specific meaning (see bit twiddling, 
    toggle). 4. Uncommon name for the twirling baton prompt.