澄む【すむ】
to become clear (water, air, etc.), to become transparent, to resonate clearly (e.g. voice), to become serene, to become tranquil, to be free of worries, to pronounce as an unvoiced sound
清澄【せいちょう】
clear, serene
澄み切る【すみきる】
to be perfectly clear (water, air, etc.), to clear up
澄まし顔【すましがお】
composed expression, clear face
澄ます【すます】
to clear, to make clear, to be unruffled, to look unconcerned, to feign indifference, to look demure, to look prim, to put on airs, to strain (one's ears), to listen carefully
研ぎ澄ます【とぎすます】
to sharpen, to grind, to whet, to hone, to make keen
澄み切った【すみきった】
perfectly clear