IPA: /ˈwɪɡliər/
KK: /ˈwɪɡlɪər/
More wiggly than something else; having a greater degree of movement or flexibility.
The worm was wigglier than the other creatures in the garden.
Comparative: wigglier
Superlative: wiggliest
Wiggly is formed from the root "wiggle" (of uncertain origin, possibly imitative of the motion) and the comparative suffix "-ier" (meaning more). The word "wigglier" means more wiggly or having a greater degree of wiggle.
Think of something that moves in a twisting or turning motion, and remember that 'wigglier' means it moves even more than usual.