Over 15 years ago, Microsoft spent half a decade trying to trademark the term "Windows." They sued a company named "Lindows" and eventually just paid them $20 million to change their name. Today, there is a long list of rules available as to how you can use the word "Windows." You could be sued if you use "Windows" in the wrong way.
Apple got a trademark for their iconic "iPod." That's understandable. But they extended it to anything with "pod" in the name and legally threatened companies that used that term.
Various well-funded companies buy up small companies with patents on small bits of computer codes. If another company, on its own, comes up with something vaguely similar, the