1.  smoothen(v = verb.contact) smooth - make smooth or smoother, as if by rubbing; "smooth the surface of the wood"
is one way to change surface
Sample sentences: Somebody ----s something; Something ----s something

2.  smoothen(v = verb.contact) polish, shine, smooth - make (a surface) shine; "shine the silver, please"; "polish my shoes"
is one way to beautify, embellish, fancify, prettify
Sample sentences: They smoothen the glass tubes

3.  smoothen(v = verb.change) - become smooth;
is one way to change
Sample sentences: Something ----s

   To make smooth. [1913 Webster]

VB  smooth, smoothen, plane, file, mow, shave, level, roll, macadamize, polish, burnish, calender, glaze, iron, hot-press, mangle, lubricate.