"Realtor Real estate agent National Association of Realtors Often used by the public, the media, and even real estate agents to refer generally to any real estate agent, but the term is a legally recognized trademark of the National Association of Realtors. The terms "Realtor" and "Realtors" refer to members of this association, and not to real estate agents generally. The National Association of Realtors is engaged in ongoing efforts to prevent the mark from becoming generic. These efforts include, among other things, writing to members of the media to complain of improper usage, distribution of information and guidelines on correct usage, and the development of an educational video on the subject.[163]"
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List of generic and genericized trademarks - Wikipedia
I have been guilty of using Xerox as a verb, and many of the listed marks such as Tupperware, Thermos, Scotch tape, Q-tips, post-it and Crock-Pot as nouns.