"confident of performance," by 1952, from expression can do "it is possible" (1903), literally "(I or we) can do (it)," which is perhaps based on earlier no can do (see no). "a person who actively seeks to correct social ills in an idealistic, but usually impractical or superficial, way," 1650s (as do-good), in "Zootomia, or Observations on the Present Manners of the English: Briefly Anatomizing the Living by the Dead. The form do-gooder appears in American English by 1922, presumably because do-good was no longer felt as sufficiently noun-like.
Also nicotin, poisonous volatile alkaloid base found in tobacco leaves, 1819, from French nicotine, earlier nicotiane, from Modern Latin Nicotiana, the formal botanical name for the tobacco plant, named for Jean Nicot (c. , sub pena, from Medieval Latin sub poena "under penalty," the first words of the writ commanding the presence of someone under penalty of failure, from Latin sub "under" (see sub-) poena, ablative of poena "penalty" (see penal).