instar

Short definition from Wiktionary

Noun

1. 1
   Any one of the several stages of postembryonic development which an arthropod undergoes, between molts, before it reaches sexual maturity.
2. 2
   An arthropod at a specified one of these stages of development.
3. 3
   A stage in development.

Verb

1. 1
   To stud or adorn with stars or other brilliants; to star.
2. 2
   To make a star of; set as a star.