stupidity (n.) Look up stupidity at Dictionary.com
1540s, "want of intelligence," from Latin stupiditatem (nominative stupiditas) "dullness, stupidity, senselessness," from stupidus "confounded, amazed; dull, foolish" (see stupid). It also at various times meant "lack of feeling or emotion" (1560s); "stupor, numbness" (c.1600).