zln -- turns greenlike Russian [zeleneyut]. Bely mixes the senses of sound and sight, combining "l" in "yellow" with the "s" sound of "cyanic blue" to achieve the Russian [zelenyi] , the color "green." In fact, many of the Indo-European languages have versions of words for "green" and "yellow" apparently derived from the same root; ghel. Cf. Buck, 1058-1059. The relation of sound to color is another of Bely's fascinations who has his own version of audition colourée such as in Rimbaud "Voyelles." Goethe was equally fascinated by color, and Steiner begins his career as a Goethe scholar. See also Bely's own analysis of colors in Russian prose in his work Masterstvo Gogolja.
vln. based on the context I have modified Bely's vin to vln which is found in his own example "volnisto."
cyanic of a blue or bluish hue. The Russian [sinii] is "dark blue," [sineva] is "bluishness." The Russian root is presumably related to "shine" [siyat']. I have found the Latin cyaneus "dark blue" which also lies at the root of English "cyan [greenish blue], cyanic, cyanogen, cyanide," etc.