fluency---> eloquence, articulacy, articulateness, expressiveness, communicativeness, coherence, cogency, intelligibility, comprehensibility, lucidity, vividness
eloquent ,inarticulacy. articulacy, facility, ability to speak or write ... easily and accurately;command of.
fluidity, flow, smoothness, effortlessness, ease, naturalness;
grace, gracefulness, elegance;
regularity, rhythm, rhythmicity;