silky envelope spun by the larvae of many insects to protect pupas and by spiders to protect eggs
source: WordNet 3.0
An oblong case in which the silkworm lies in its chrysalis state. It is formed of threads of silk spun by the worm just before leaving the larval state. From these the silk of commerce is prepared.
source: Webster 1913
verb
retreat as if into a cocoon, as from an unfriendly environment
Families cocoon around the T.V. set most evenings. She loves to stay at home and cocoon.
