Vanishing or likely to vanish like vapor.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "evanescent" in a sentence
"These might well be termed evanescent varieties, and since they never become fixed or find their way into cultivation they are of interest only to the plant breeder."
"In part, it arises because an exotic form of light wave generated at the interface, called an "evanescent" wave, is lost in passing through the glass of a lens, with a consequent loss of information and a slight spoiling of image sharpness."
"Ridicule and derision are a kind of evanescent ostracism, a temporary exclusion from the comradeship."