The word 'wiggly' is built upon the expressive verb 'wiggle', which emerged in Middle English to describe a specific kind of restless, jerky motion. The root 'wigg-' is likely of Germanic origin, related to similar words in Dutch and Low German for wobbling or tottering, suggesting a deep-rooted, onomatopoeic or imitative sense of unsteady movement. The adjectival suffix '-ly', from Old English '-līc', is attached to transform the action into a descriptive quality, meaning "having the characteristics of wiggling". Thus, 'wiggly' logically describes anything that exhibits the quick, sinuous, or unstable motion inherent in its core root, from a wiggly worm to a wiggly tooth or even a wiggly line drawn by hand.

Structure: wigg (to move jerkily) + ly (adjective-forming suffix) - wigg: Origin: Middle English wiglen (to wiggle), likely from Middle Dutch or Middle Low German wiggelen (to totter, wobble). Role: Core root conveying the sense of quick, small, irregular movements. - ly: Origin: Old English -līc (having the form or quality of). Role: Suffix used to form adjectives from nouns or other adjectives, meaning "characterized by" or "resembling".