At the time the phrase was common, "back in the world" usually meant back in the United States, although it could refer to any other part of the so-called civilized world which was equipped with such things as ice machines, clean sheets, hot and cold running whatever, and television. "Incountry" was a term reserved for the war zone -- generally Viet Nam, occasionally Cambodia or Laos. More recently, the common military definitions of both terms have become rather more generalized: "the world" is usually one's normal territory, with "incountry" used as a reference for the location of whatever armed conflict is currently ongoing, or lacking that, any seriously hazardous locale. -- Reno