maverick

A person who shows independence of thought and action, especially by refusing to adhere to the policies of a group to which he or she belongs.

An unbranded range animal, especially a calf that has become separated from its mother, traditionally considered the property of the first person who brands it.

Characterized by or displaying independence of thought and action.

To seize or brand (an animal) as a maverick; hence, to take possession of without any legal claim; appropriate dishonestly or illegally.

On the great cattle-ranges of the United States, an animal found without an owner's brand, particularly a calf away from its dam, on which the finder puts his own or his employer's brand; or one of a number of such animals gathered in a general round-up or muster of the herds of different owners feeding together, which are distributed in a manner agreed upon.