1. To work with or modifY in a not particularlY serious manner. "I diddled a copY of ADVENT so it didn' t double-space all the time." "Let' s diddle this piece of code and see if the problem goes awaY." See tweak and twiddle. 2. The action or result of diddling. See also tweak, twiddle, frob. [Jargon File] (1995-01-31)