souvenir (n.) 1775, "a remembrance or memory," from French souvenir (12c.), from Old French noun use of souvenir (v.) "to remember, come to mind," from Latin subvenire "come to mind," from sub "up from below" (see sub-) + venire "to come," from a suffixed form of PIE root *gwa- "to go, come."

According to the Oxford English Dictionary, the word souvenir in English originally comes from French, where it has a long history. Appearing first in Old French around 1100 CE as suvenir, the word was used as a noun to mean “ (something) in one’s memory.”