見澄ます[misumasu] to observe carefully
耳を澄ます[mimiwosumasu] to listen carefully
上澄[uwazumi] the clear top of a liquid
澄まし屋[sumashiya] a prim person
澄まし顔[sumashigao] composed expression

澄ます[sumasu] to clear
澄みきる[sumikiru] to be serene
澄み渡る[sumiwataru] to be perfectly clear
澄む[sumu] to clear (e.g. weather)
清澄[seichou] clear