Source : WordNet®

crystal clear
     adj 1: transmitting light; able to be seen through with clarity;
            "the cold crystalline water of melted snow"; "crystal
            clear skies"; "could see the sand on the bottom of the
            limpid pool"; "lucid air"; "a pellucid brook";
            "transparent cristal" [syn: {crystalline}, {limpid}, {lucid},
             {pellucid}, {transparent}]
     2: (of language) transparently clear; easily understandable;
        "writes in a limpid style"; "lucid directions"; "a
        luculent oration"- Robert Burton; "pellucid prose"; "a
        crystal clear explanation"; "a perspicuous argument" [syn:
         {limpid}, {lucid}, {luculent}, {pellucid}, {perspicuous}]