essayyoudaoicibaDictYouDict[essay 词源字典]
essay: [15] Essay and assay [14] are fundamentally the same word, and only began to diverge in the 15th century. Both come via Old French assaier from Vulgar Latin *exagiāre ‘weigh out’, a verb derived from late Latin exagium ‘weighing’; this in turn was formed from the Latin verb exigere ‘weigh’ (source of English exact and examine).

Accordingly, both originally had underlying connotations of ‘testing by weighing’. But while these have become more concrete in assay ‘analyse precious metals’, essay has, under the influence of French essayer, gone down the more metaphorical route from ‘test’ to ‘try’. The verb now survives only in fairly formal use, but the noun is much more frequent, owing to its application to a ‘short nonfictional literary composition’.

It was first used thus in English by Francis Bacon in 1597 as the title of a collection of such pieces, and it is generally assumed that he borrowed the idea from the Essais of Montaigne, published in 1580.
=> assay, exact, examine[essay etymology, essay origin, 英语词源]
non-fiction (adj.)youdaoicibaDictYouDict
also nonfiction, 1866, a librarians' word, first in the reports of the Boston Public Library, from non- + fiction. Apparently not in widespread use until after 1900.