The term 'internal' can be defined by a variety of crossword solutions. INTRINSIC is a nine letter solution meaning 'belonging to the essential nature or constitution of a thing'. DOMESTIC is an eight letter solution meaning 'relating to the HOME or household'. INHERENT is another eight letter solution meaning 'existing in something as a permanent, essential, or characteristic attribute'. HOME is a four letter solution meaning 'the place where one lives permanently'. INSIDE is a six letter solution meaning 'on or toward the INNER side or within'. GUT is a three letter solution meaning 'the part of the alimentary canal between the stomach and the anus'. CENTRAL is a seven letter solution meaning 'of or relating to a center'. INWARD is a six letter solution meaning 'directed or moving toward a center or INWARD part'. INNER is a five letter solution meaning 'situated within or farther within'.