sheath

nouns

a protective covering (as for a knife or sword)
sheath
is a type of (narrower)
a covering that is intend to protect from damage or injury
"they had no protection from the fallout"; "wax provided protection for the floors"
protection, protective cover, protective covering
an enveloping structure or covering enclosing an animal or plant organ or part
case, sheath
a dress suitable for formal occasions
cocktail dress, sheath