Definitions for eclosionɪˈkloʊ ʒən
Random House Webster's College Dictionary
the emergence of an adult insect from its pupal case.
the hatching of a larva from its egg.
Origin of eclosion:
1885–90; < F éclosion, der. of éclos, ptp. of éclore to hatch
The emergence of an insect from the pupa case, or of a larva from the egg