Smoothly means evenly and without any trouble. Run smoothly, went smoothly, speak smoothly.
Applied to a person it turns critical — talking smoothly suggests polish covering something. Applied to a process it is simple praise. Everything went smoothly is the standard report when there is nothing to report.
1adverbsmoothlyEvenly and without any trouble.
“The engine runs smoothly now that the mechanic has fixed it.”
smoothly is a manner.
Smooth plus -ly, from Old English smoth, of uncertain further origin.
Middle English
smoþely
English, today
smoothly
From Middle English smoþely; equivalent to smooth + ly.
Etymology from Wiktionary, CC BY-SA