In order for a "thing" (word, logo design, or other device) to serve as a trademark, and thereby receive legal protection, that "thing" must meet these requirements:

  1. Used in commerce before another confusingly similar trademark.  That use must be in inter-state commerce to be eligible for federal registration and protection.
  2. Not descriptive, or otherwise has acquired secondary meaning
  3. Not deceptive, mis-descriptive or falsely suggesting an affiliation
  4. Not disparaging of a person, institution, belief or national symbol
  5. Not comprised of a flag or govt. insignia
  6. Not a name, portrait or signature of a living person or dead president
  7. Not primarily a functional feature

NOTE:  In the United States, registration is NOT required. Most other non-English-speaking countries in the world require trademark registration in order for a device to be recognized and protected as a trademark.  Most the above requirements are spelled out in the Lanham Act that the US Trademark Office follows for determining whether or not a mark can be federally registered.  Each state and even each federal circuit may allow and protect a device even if the Trademark Office would not.