territorial
n.n. used to describe an animal or person that protects its own area and does not want others to enter it. You use this when someone feels very protective of their space or things.
n. relating to the ownership or defense of a specific area of land. Describes behavior intended to exclude others from a particular geographic space or social domain.
The male bird becomes very territorial during the spring.
Some dogs are naturally territorial and will bark at anyone who walks past the front gate of their home.
While many species share resources peacefully, others exhibit highly territorial displays to ensure they maintain exclusive access to the best nesting sites and food sources within their range.
Typically placed before the noun it modifies; often followed by the preposition 'about' when describing human behavior.