How can someone own the right to a word?

This is an interesting question and one I've enjoyed looking into. The short answer is there is no legal way for a person to own a word, and without the support of legal recourse, there is no way to enforce repercussions for perceived misuse or infringement. However, businesses and entrepreneurs can trademark common words under certain circumstances. The following two characteristics must be met before a company can own trademark rights to a common word:
The word must be an identifying factor of the company in its industry. For example, APPLE could be trademarked by Apple, Inc because people had already come to identify the company by that brand name in the computer and technology industry. It is important to note though that the company's trademark rights only extend to other companies in that industry. Businesses outside of computer and technology still have equal rights to trademark that word if they so desire. 
The word must not directly relate to the industry of the business seeking trademark rights. Back to our Apple, Inc example: The word APPLE has absolutely nothing to do with computers or technology so it is available as a term to be trademarked in that industry. It would be inappropriate for an apple farmer to try to trademark the word because it would infringe on the rights of others in the produce industry to properly market their products. If only one fruit company could use the word APPLE in marketing, that fruit company would soon have a monopoly on the apple industry. 
So while you cannot actually own a word, you can trademark one if it helps identify your business to consumers and it doesn't infringe on the rights of others in your industry. 
https://creekmorelaw.com/you-can-own-a-trademark-but-you-cant-own-a-word/

https://secureyourtrademark.com/can-you-trademark/common-words-phrases/