1. interstage - Noun
2. interstage - Adjective
(astronautics) The structure, generally containing mechanical components and instruments but no engines or fuel tanks, connecting the top of a stage of a multistage rocket to the bottom of the stage above it.
(military) The components of a multistage thermonuclear weapon which channel the radiation produced by the primary's fission explosion so as to trigger the implosion of the secondary and ignite a fusion explosion in the secondary's fusion fuel.
interstage (not comparable)
Between stages.
In the 1920s, commercial IF filters looked very similar to 1920s audio interstage coupling transformers, had very similar construction and were wired up in an almost identical manner, and so they were referred to as "IF transformers". Source: Internet
These normally operate as a single stage without nozzle and interstage guide vanes. Source: Internet