The Collaborative International Dictionary of English v.0.48:

Squiggle \Squig"gle\ (skw[i^]g"g'l), v. i. [Cf. Prov. E. swiggle
   to drink greedily, to shake liquor in a close vessel, and E.
   swig.]
   To shake and wash a fluid about in the mouth with the lips
   closed. [Prov. Eng.] --Forby.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Squiggle \Squig"gle\, v. i. [Cf. Squirm, Wiggle.]
   To move about like an eel; to squirm. [Low, U.S.] --Bartlett.
   [1913 Webster]

WordNet (r) 3.0 (2006):

squiggle
    n 1: a short twisting line [syn: squiggle, curlicue]
    2: an illegible scrawl; "his signature was just a squiggle but
       only he could make that squiggle"