Douglas Harper's Etymology Dictionary
wash-out
also washout, 1877, "act of washing out" (a drain, etc.), from verbal phrase; see wash (v.) + out (adv.). From 1873 as "excavation of a roadbed, etc., by erosion" is from 1873. Meaning "a disappointing failure" is from 1902, from verbal phrase wash out "obliterate, cancel" (something written in ink), attested from 1570s. Hence also the colloquial sense of "to call off (an event) due to bad weather, etc." (1917). Of colored material, washed-out "faded" is from 1837.
Wiktionary
wash-out
n. (alternative form of washout English)
Usage examples of "wash-out".
The plan of campaign, he decided, had been a great deal too elaborate, and his part looked like a wash-out.