adj

• (obsolete or poetic) Overtaken by night; especially of a traveller, etc.: caught out by oncoming night before reaching one's destination.
  "The Porter anſwered, This Man is in a Journey from the City of Deſtruction to Mount Zion, but being weary, and benighted, he asked me if he might lodge here to night; ſo I told him I would call for thee, who after diſcourſe had with him, mayeſt do as ſeemeth thee good, even according to the Law of the Houſe."
• (obsolete) Plunged into darkness.
  "Rob the Spheare of lines vnited, / Make a ſuddaine voide in nature: / Force the day to be benighted, / Reaue the cauſe of time and creature."
• (figuratively) Lacking education or knowledge; unenlightened; also, lacking morality; immoral, unscrupulous.
  "[I]t would be difficult to name any writers who have contributed so much to promote the progress of civilization as "these illustrious authors—these friends of human nature—these kind instructers of human errors and frailties—these benevolent spirits, who held up the torch of science to a benighted world.""
• (figuratively, obsolete) Difficult to understand; abstruse, obscure.
  "[O]thers, held very good men, are at a dead ſtand, not knovving vvhat to doe or ſay; and are therefore called Seekers, looking for nevv Nuntio's from Chriſt, to aſſoil theſe benighted queſtions, and to give nevv Orders for nevv Churches."