> TGV stands for train à grande vitesse, or “train of great speed.”
This is one of my pet peeves. Train à grande vitesse means high-speed train in English. There's no need to provide a mechanical word by word translation. It's like people saying al dente means "to the tooth" which is meaningless in English. Being al dente means something has bite. This kind of thing should only be a problem if the target language has no translation.
English has no literal word-to-word equivalent to this - this french "à" is used to describe the main property of a noun, and the translation in English when no original word exists is via a nominal group or a concatenation of nouns. An "avion à hélice" is a propeller plane, a "bateau à vapeur" is a steamboat, or an "étui à lunettes" is a glasses case. So a "train à grande vitesse" is similarly just a high-speed train.
"of" in English here sounds like you're describing what the object is made of instead of its property. A "boat of steam" is made of steam, it's not the same as a steam boat.
You don't translate it, that's the point. Train à grande vitesse means high-speed train. There is no "of", "at" or "with" there.
Similarly, pain au chocolat does not mean "bread of the chocolate" or anything silly like that. "Chocolate bread" would be the closest translation but since this is ambiguous in English we just use the French word as a loanword.
You won't learn anything by trying to find an English analogue for words like à in French. It will probably actually set you back. You just have to learn it how natives learn it. It's French because it's French. There is no other definition and you can't draw on any other language for guidance. This goes for all natural languages.
It's not the "of", it's just that "grande vitesse" means "high speed", it doesn't have the undertones that "great" has in English. Unless I'm overinterpreting the meaning in English (French is my native language, not English).
It doesn't bother me that much really but if we want to be pedantic the literal rendering would be be "train at great speed" - this would make your point more pronounced.
If you want to be pedantic, the preposition à serves about twenty different roles (per the dictionary), so even a literal translation will have to pick the right word, not just one of its homonyms.
At is not the right word, even if you're translating word by word.
I just wanted to reply how wrong you are and that the OP's version would be literal if "de" was used instead of "à" but just writing that made me realize that I'm completely wrong and you are totally right. That's a rare moment and I decided to celebrate it by making this comment. Thank you!
This is one of my pet peeves. Train à grande vitesse means high-speed train in English. There's no need to provide a mechanical word by word translation. It's like people saying al dente means "to the tooth" which is meaningless in English. Being al dente means something has bite. This kind of thing should only be a problem if the target language has no translation.