challenge (n.) Look up challenge at Dictionary.com
early 14c., "something one can be accused of, a fault, blemish;" mid-14c., "false accusation, malicious charge; accusation of wrong-doing," also "act of laying claim" (to something), from Anglo-French chalenge, Old French chalonge "calumny, slander; demand, opposition," in legal use, "accusation, claim, dispute," from Anglo-French chalengier, Old French chalongier "to accuse, to dispute" (see challenge (v.)). Accusatory connotations died out 17c. Meanings "an objection" in law, etc.; "a calling to fight" are from mid-15c. Meaning "difficult task" is from 1954.
challenge (v.) Look up challenge at Dictionary.com
c.1200, "to rebuke," from Old French chalongier "complain, protest; haggle, quibble," from Vulgar Latin calumniare "to accuse falsely," from Latin calumniari "to accuse falsely, misrepresent, slander," from calumnia "trickery" (see calumny).

From late 13c. as "to object to, take exception to;" c.1300 as "to accuse," especially "to accuse falsely," also "to call to account;" late 14c. as "to call to fight." Also used in Middle English with sense "claim, take to oneself." Related: Challenged; challenging.