Definition of smooth-running:
(adj) :
Having a texture that lacks friction. Not rough.
(adj) :
Without difficulty, problems, or unexpected consequences or incidents.
(adj) :
Bland; glib.
(adj) :
Flowing or uttered without check, obstruction, or hesitation; not harsh; fluent.
(adj) :
Suave; sophisticated.
(adj) :
(of an action) Natural; unconstrained.