(as) smooth as glass American British informal
1. Used to indicate the water in a state of calm and tranquility.
With no wind, the lake was completely as smooth as glass.
The surface of the water is as smooth as glass, reflecting the sunbeams back to my face.
2. Used to indicate some solid surface that is very smooth.
I sanded the wooden door for days until it was smooth as glass.
The carpenter rubs a rough piece of wood as smooth as glass.
Used to advise somebody to calm down
To help something run or work smoothly or successfully
Completely smooth
Used to describe someone kind, calm and pleasant