Synonyms for Flyaway (same or very similar meaning)
WordNet sense 1 (guided by whim and fancy):
flighty, scatterbrained, head-in-the-cloudsWordNet sense 2 (not serious in content or attitude or behavior):
frivolousWordNet sense 3 (not tight; not closely constrained or constricted or constricting):
looseFrom the ODE community, based on WordNetadd/edit