substage

/ˈsʌbˌsteɪdʒ/
noun
  1. A part or step within a larger stage of a process or development.
    • In child development, crawling is a substage of the larger motor skills stage.
    • The project has several substages, starting with research and ending with testing.
    • Each substage of the manufacturing process must be checked for quality.
  2. The part of a microscope that holds the condenser, filters, or other equipment below the stage.
    • She cleaned the lens on the substage before starting the experiment.
    • He adjusted the substage to improve the lighting on the slide.
    • The microscope's substage contains a condenser that focuses light onto the specimen.