STOMACH (στόμαχος, G5126). The upper digestive tract. “Stomach” in RSV is occasionally the tr. of Heb. or Gr. terms more accurately rendered “bowels” or “belly,” that part of the body between the lower ribs and the groins. As the seat of physical satisfaction or lust it is mentioned in Proverbs 13:25; Jeremiah 51:34; Ezekiel 3:3; Luke 15:16; Romans 16:18; and Philippians 3:19. In the latter two cases the reference is to those who give first place to physical appetites.
The exact term is used only in the NT by Paul, who advised Timothy to “use a little wine for the sake of your stomach and your frequent ailments” (1 Tim 5:23). The term is used also in 2 Maccabees 7:21 to mean “courage.” See also Belly.
International Standard Bible Encyclopedia (1915)
In man and most vertebrates, a membranous sac-like portion of the alimentary canal, in which the earlier stages of digestion take place and in which food is prepared to yield its nourishment (1Ti 5:23).
Used figuratively of pride, "A proud look and high stomach" (Ps 101:7, Prayer-book Version), and courage, "Stirring up her womanish thoughts with a manly stomach" (2 Macc 7:21 the , the (British and American) "with manly passion").