The Collaborative International Dictionary of English v.0.48:

Noddle \Nod"dle\, n. [OE. nodil, nodle; perh. fr. nod, because
   the head is the nodding part of the body, or perh. akin to E.
   knot; cf. Prov. E. nod the nape of the neck.]
   1. The head; also, noodle; -- used jocosely or
      contemptuously.

   Syn: noggin.
        [1913 Webster +PJC]

              Come, master, I have a project in my noddle.
                                                  --L'Estrange.
        [1913 Webster]

   2. The back part of the head or neck. [Obs.]
      [1913 Webster]

            For occasion . . . turneth a bald noddle, after she
            hath presented her locks in front, and no hold
            taken.                                --Bacon.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Noodle \Noo"dle\, n. [Cf. Noddle, Noddy.]
   1. A simpleton; a blockhead; a stupid person; a ninny. [Low]
      [1913 Webster]

            The chuckling grin of noodles.        --Sydney
                                                  Smith.
      [1913 Webster]

   2. The head; also, noddle; -- used jocosely or
      contemptuously; as, use your noodle.

   Syn: noggin.
        [PJC]

WordNet (r) 3.0 (2006):

noddle
    n 1: an informal British expression for head or mind; "use your
         noddle"

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "noddle":
   bean, belfry, brain, brow, conk, crown, dome, encephalon,
   gray matter, head, headpiece, noggin, noodle, organ of thought,
   pate, poll, ridge, sconce, seat of thought, sensation, sensorium,
   sensory