Synonyms for Fluent (same or very similar meaning)
WordNet sense 1 (smooth and unconstrained in movement):
fluid, liquid, smoothWordNet sense 2 (characterized by beauty of movement, style, form, or execution):
gracefulWordNet sense 3 (expressing yourself readily, clearly, effectively):
eloquent, facile, silver, silver-tongued, smooth-spokenFrom the ODE community, based on WordNetadd/edit