A political entity that formally agrees by treaty to enter into an unequal relationship with another, stronger state, called the protector, which engages to protect it against third parties, in exchange for which the protectorate usually accepts specified obligations, which may vary greatly, depending on the real nature of their relationship. (source: Wikipedia)
a territory controlled by (but not a possession of) a stronger state
a state or territory partly controlled by (but not a possession of) a stronger state but autonomous in internal affairs; protectorates are established by treaty