How should you name an imaginary machine? I was thinking of naming a time-machine/transdimensional teleportation machine Proteus, but I am not sure if giving it a generic name like that makes sense. It's because the time machine allows you to travel in time, travel at any location in the present and change dimensions, so I was wondering if there's a better way in naming it. I can't refer to it as a time-machine, because it's much more and describing it as a "time-machine/transdimensional teleportation machine" is a mouthful and sounds weird.
I would name it "George."
Jokes aside, it's a fantasy machine. You can name it whatever you want, even if it doesn't make conventional sense, like Proteus. Prometheus, the Titan of Forethought, might make more sense, but Ultimately, if you think Proteus rolls off the tongue and does the job you want it to do, who's to stop you?
How your character in a position to give it a name would decide:
Depends on what you want to use the name for, besides being a shortened version of "my spacio-temporal teleportation thingamabob."
If you are a scientist who wants people to KNOW that it is, the long name is the correct thing.
If you want a selling point, you give it a lyrical name that invokes its traveling powers. Far-farer, Portal to the Universe, Wanderer.
If you want a code name that will hide its nature from ill-natured eavesdroppers, you give it something that doesn't hint at its abilities. Proteus, for instance, though that may make them think it's a shape-shifting machine instead. Butterfly. Keyring.
If you just want a nickname, the sky's the limit. You could name it Bob, or Hephzibah, or Spot, or Goldfish. . . .
Different characters, having different motives, could use different names. Dr. Looney calls it the Far-farer, and his assistants, out of earshot, call it Looney's Folly.
In the same vein as the FLDSMDFR (pronounced "fle-dsum-de-ferr"), you can really do whatever you like. Given that you call it a "time-machine/transdimensional teleportation machine", you can go with "TMTTM" (pronounced "tum-tum") of "TMTDMM" (pronounced "tum-te-dum").
Naming is often a matter of matching the tone of your story rather than some universal correct nomenclature. Cloudy With A Chance Of Meatballs centered around a wacky, annoyingly awkward inventor, so they made him use a wacky and annoyingly awkward name for his inventions.
Another example, Tony Stark is known for his diminutive attitude towards others. His creation, JARVIS, is not named after some godly entity. He named him after his butler, telegraphing exactly how Tony was expecting JARVIS to relate to him: a servant, albeit a very reliable and loyal one.
Another example, Rick Sanchez called the self-aware robot he built simply because he did not want to get up to get the butter "Butterbot". Why? Because Rick constantly slaps things together in the most nonchalant way for a specific purpose, and spends no time on anything other than the specific purpose. The name "Butterbot" shows exactly how little forethought Rick put into the robot. This was not a long term project, it was a quick hackjob. The naming reveals Rick's attitude towards his creations: straghtforward, onedimensional, expendable, slapdash.
Based on you picking "Proteus" as a working name, I'm going to guess that the tone of your story (or at least the character who comes up with the name in-universe) is one of academic knowledge and reverence for the power of the machine, so stick with that theme. It doesn't have to be pedantically correct in every possible interpretation and every possible feature of the machine.
Take the Dilbert route and name it something trendy.
The Gruntmaster 6000. An exercise machine with a built in graviton generator to control the amount of weight you lift. Same hardware as the Gruntmaster 4000, but software upgradeable.