Definition of instar:
(n) :
Any one of the several stages of postembryonic development which an arthropod undergoes, between molts, before it reaches sexual maturity.
(n) :
An arthropod at a specified one of these stages of development.
(n) :
(by extension) A stage in development.
(v) :
(transitive) To make a star of; set as a star.
(v) :
(transitive, archaic) To stud or adorn with stars or other brilliants; to star.