tagma

noun3

1. •
   A specialized, structured, grouping of functionally related segments, or analogous subunits, into units such as the head, the thorax, and the abdomen, particularly in various Arthropoda and Vertebrata.
2. •
   (old-fashioned) A specialized, structured, grouping of functionally related molecules, forming the basis the physiology and structure of larger units such as cells and tissues.
3. •
   (historical) A military unit of battalion or regiment size, in the Byzantine empire of the 8th–11th centuries.