"the theory that art and literature should strictly reproduce truth," 1892, from Italian verismo, from vero "truth," from Latin verus "true" (from PIE root *were-o- "true, trustworthy") + -ismo, Italian form of -ism.
It is the hypothetical source of/evidence for its existence is provided by: Latin verus "true;" Old Church Slavonic vera "faith," Russian viera "faith, belief;" Old English wær "a compact," Old Dutch, Old High German war, Dutch waar, German wahr "true;" Welsh gwyr, Old Irish fir "true."
word-forming element making nouns implying a practice, system, doctrine, etc., from French -isme or directly from Latin -isma, -ismus (source also of Italian, Spanish -ismo, Dutch, German -ismus), from Greek -ismos, noun ending signifying the practice or teaching of a thing, from the stem of verbs in -izein, a verb-forming element denoting the doing of the noun or adjective to which it is attached. For distinction of use, see -ity. The related Greek suffix -isma(t)- affects some forms.
<a href="https://www.etymonline.com/word/verism">Etymology of verism by etymonline</a>
Harper, D. (n.d.). Etymology of verism. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/verism