Note: I am not an expert in immaterial or name law.
Trademark law basically states that you may not use someone else's trademark to free-ride on their reputation. The key issue is if the inappropriate use is confusable with the owner's name, brand, product or service.
But there is never anything as a simple law: There are several international treaties as well as national laws governing brands, trademarks and names, so I will only speak in broad terms reflecting on the Swedish implementation of the EU regulations, to the best of my knowledge.
Let's start talking about what is a Trademark:
A Trademark can be anything that can be visualized - a letter, word or glyph. Most commonly, brands are considered Trademarks. There is a distinct difference between a regular Trademark (TM) and a Registered Trademark (R). To get a Registered Trademark, one have to file with the appropriate patent/trademark organization and get approved. On the other hand, anyone can put a (TM) next to whatever they want to or simply stating "HüllårFøllör is trademark by ACME Music Inc." BUT: it will not explicitly forbid anyone to use the trademark. The (TM) or statement is merely an indicator that the "owner" of the trademark will probably go to court if you try to free-ride on it.
Will the "owner" win? It depends on how well-known and distinct the Trademark is within its target audience for its domain: For example, HüllårFøllör(TM) might be a Trademark within the music domain but not within a car domain, because petrolheads don't know that HüllårFøllör is the name of the coating used on certain guitarstrings made by ACME Music Inc.
Ok, on with some real examples:
"Nobel Prize" is (R), so making a programming language called NobelPrize will definitely get you into trouble, but making a program called NobelPrizeLaureatesLister which lists laureates most likely won't - it's fair use of the "Nobel Prize" trademark (I guess).
To make it worse, the Japanese camera manufacturer Canon Inc. holds the Trademark for the "Canon" name. But, Canon has a lot of other meanings as well, such as a title of certain Christian priests.
So, would your fictitious language Canon violate the Trademark of Canon Inc.? It depends on which kind of Canon your Canon language is named from.
Generic words can not be trademarked: It is not possible to trademark the word "hello" as such. However, when combined with other generic words in order to specialize the words, such as "glue", "Hello Glue" can be trademarked. But ... you can trademark a logotype consisting of the word "hello".
Therefor, a language can be called Python (since it is a generic word), or Monty (since it also is a generic word or a name), but not "Monty Python", since that can be a specialization, especially in the domains of comedy, music, film and theater.
To make it even harder, a Trademark owner must also enforce it. Bayer AG lost its trademark of Aspirin, since it didn't attack competitors that produced and sold other pain-relievers under the name Aspirin. Hence, "aspirin" is now considered a generic word, free for use in several countries.
But what about homage to persons?
Let's name our language Ericsson, after Lars Magnus Ericsson (namesake for the international telecom company "Telefonaktiebolaget LM Ericsson", most commonly known as Ericsson).
That is perfectly fine according to Swedish trademark and name-law, since it is not possible to trademark a commonly name unless it is "distinct and unique". Which Ericsson certainly isn't in Sweden. BUT: It is illegal to use a person (such as Lars Magnus Ericsson himself, had he still been alive) to promote and advertise your language, unless he agrees to.
Hence, "Telefonaktiebolaget LM Ericsson" does not own a trademark on the name Ericsson - but the Ericsson "three sausages" logo which consist of the ///-symbol and the word Ericsson written below it, is trademarked.
However, naming your language Nobel, in homage to Alfred Nobel is not allowed according to Swedish name law, since Nobel is a "distinct and unique" name. The Nobel Foundation can (and will) go to court in case you try to use Nobel.
But then again, you might think that "grape" is a generic word for something that can be pressed and fermented into wine, so you want to use "Kicking grape" as the trademark for your wine? Not so, because Grape is a distinct and unique family name in Germany and Sweden.
All these languages, countries and laws... Things aren't meant to be easy, are they?
One way I've dealt with the issue, is to simply check if myintendedname is registered as a .com domain. If not, it's probably free for use.
