cleidoic
adjective
clei·do·ic klī-ˈdō-ik 
of an egg
: enclosed in a relatively impervious shell which reduces free exchange with the environment
Word History
Etymology
Greek kleidoun to fasten, lock in, from kleid-, kleis key — more at clavicle
First Known Use
1929, in the meaning defined above
Medical Definition
cleidoic
adjective
clei·do·ic klī-ˈdō-ik
of an egg
: enclosed in a relatively impervious shell which reduces free exchange with the environment
the eggs of birds are cleidoic