1. An independent thinker who refuses to conform to what are considered to be "accepted views" on a subject or somwone who exhibits great independence in thoughts and actions; a dissenter: The mayor tended to be a maverick in terms of cooperating with the other members of the city council.
2. Etymology: from 1867, "a calf" or "range animal" or "stray calf" found without an owner's brand, which referred to Samuel A. Maverick (1803-1870), a Texas cattle owner who became famous for not branding his calves.

Mr. Maverick's cattle were left unidentified and free to roam, and so they were often "adopted" by other ranchers who termed them mavericks, and by the end of the century the term maverick had come to mean "any kind of wanderer or nonconformist".

The sense of being "an individualist" or being "unconventional" was first recorded in 1886, via the notion of being without any kind of control.