Origin: 1400–50; late Middle English < Middle French < Late Latin rēctitūdin- (stem of rēctitūdō) straightness, equivalent to Latin rēct(us) right + -tūdin--tude
early 15c., "quality of being straight," from M.Fr. rectitude (14c.), from L.L. rectitudinem (nom. rectitudo) "straightness, uprightness," from L. rectus "straight" (see right). Sense of "upright in conduct or character" is from 1530s.