Is Fahrenheit a real word in German? Does it come from a concept or from a name?
The German physicist Daniel Gabriel Fahrenheit was the eponym for the temperature scale still used today. This is an excerpt from his famous publication on the freezing point of water:
As the other answers have already pointed out, "Fahrenheit" is simply the name of the physicist who invented that temperature scale.
However, since the German language makes good use of word compositions, one could try to construct something from its only possible parts, "Fahren" and "Heit".
"Fahren" is an infinitive form of a verb and can be translated to "to drive".
"Heit" is only used as a word suffix DE: link is in German only in Standard German, often describing a condition specified by its prefixed word. For example, "Schönheit" will describe the condition of being "schön", i.e. beautiful. You will find "-heit" mostly in conjunction with an adverb, sometimes also a noun, but not a verb such as "fahren". In English, a related suffix would be "-ness" (as in happiness) or "-hood" (as in childhood).
So no, even if you would decompose it syntactically, the word "Fahrenheit" wouldn't make much sense.
The closest nonsensical English translation would be something like "drive-hood" or "drive-ness".
A quick search leads to a possible explanation:
In this light, "Fahren" could be derived from "varen", which could be Low German for "vor dem"DE, translated to "in front of the".
"Heit" might be an old or Low German spelling of "Heide"DE, which translates to "heath" or "moor".
So maybe the family lived at a place near a moor or heath, and that's where their name came from.
No, Fahrenheit is just a proper name - not even a very common in Germany. Daniel Fahrenheit was Prussian physicist who proposed the temperature scale in 1714. It's worth mentioning that the Celsius scala is the official one in Germany though.
The only meaning you'll find in a dictionary is - like in English - the Grad (degrees) Fahrenheit.
As others have pointed out, "Fahrenheit" is a proper name. According to the Online Etymology Dictionary, that is
An abstract surname meaning literally "experience."
This suggests that the name is a short form of "Erfahrenheit" which would be more precisely translated as "the state of being experienced".
Fahrenheit, Celsius, Réaumur and Kelvin were all physicists whose names have been used to name a temperature scale. None of these words has any meaning in German, except as their use in naming temperatures, like
Eis schmilzt bei null Grad Celsius oder 32 Grad Fahrenheit.
Any attempts to pull the word Fahrenheit apart and trying to give it any meaning based on the parts is nonsense.