duplicity (n.) Look up duplicity at Dictionary.com
early 15c., from Old French duplicite (13c.), from Late Latin duplicitatem (nominative duplicitas) "doubleness," in Medieval Latin "ambiguity," noun of quality from duplex (genitive duplicis) "twofold," from duo "two" (from PIE root *dwo- "two") + -plex, from PIE root *plek- "to plait." The notion is of being "double" in one's conduct (compare Greek diploos "treacherous, double-minded," literally "twofold, double").