usage: powerful and effective language; "his eloquence attracted a large congregation"; "fluency in spoken and written English is essential"; "his oily smoothness concealed his guilt from the police"
usage: the quality of being bland and gracious or ingratiating in manner
4. smoothness, evenness, invariability
usage: the quality of having a level and even surface; "the water was a glassy smoothness"; "the weather system of the Pacific is determined by the uninterrupted smoothness of the ocean"
5. smoothness, effortlessness
usage: the quality of being free from errors or interruptions; "the five-speed manual gearbox is smoothness personified"