"smoother"
2 occurrences in KJV
Proverbs 5:3
For the lips of a strange woman drop as an honeycomb, and her mouth is smoother than oil:
Psalms 55:21
The words of his mouth were smoother{H8804)} than butter, but war was in his heart: his words were softer{H8804)} than oil, yet were they drawn swords.