(rare) shield (anything which protects or defends)

guardian; protector, a person legally responsible for a minor (in loco parentis) or an incompetent person.

(computing) character whose appearance may depend on a user's environment, or a character which may be absent from a user's environment, i.e. character set incompatibility

UNEP, United Nations Environment Programme

engage in an extravehicular activity

extravehicular activity

nature reserve