late 14c., "state or fact of forgetting," from Old French oblivion (13c.) and directly from Latin oblivionem (nominative oblivio) "forgetfulness; a being forgotten," from oblivisci (past participle oblitus) "forget," originally "even out, smooth over, efface," from ob "over" (see ob-) + root of levis "smooth," from PIE *lei-w-, from root *(s)lei- "slime, slimy, sticky" (see slime, n.). Meaning "state of being forgotten" is early 15c.