Does the word “uzi” need to be capitalized?
Why is Uzi capitalized? It comes from a name, and people haven't frequently used it in lowercase in publication.
First, the name is derived from a person's name. These usually retain their capitalization. For example, we have:
- Tommy gun, or the Thompson submachine gun, for inventor John T. Thompson (Wikipedia)
- Molly or Molotov cocktail, in mockery of Soviet foreign minister Vyacheslav Molotov (Wikipedia)
- The Luger, for inventor Georg Luger (Wikipedia)
Even though they come in multiple models and forms, the type of weapon retains the capitalization of the name, even if it's not also the name of the manufacturer.
Furthermore, Uzi hasn't generalized to the point of being lowercase, like some other products. For example, we have:
- diesel, in diesel fuel and diesel engines, for inventor Rudolf Diesel (Wikipedia)
- leotard, for performer Jules Léotard (Wikipedia)
- voltaic pile, for physicist Alessandro Volta (Wikipedia)
Popularity makes lowercase more likely, but shifts in usage are arbitrary and vary between individual words. For instance, Ferris wheels are well-known, but the name retains the capitalization.
With Uzi, too, the capitalization remains: in a News on the Web Corpus search, among 2226 results for "uzi," virtually all results are "Uzi." Only 31 of the first thousand results were lowercase. So it will be a while before one can build an argument for "Uzi" being a valid Scrabble word.
Proper noun or not, this is an item that borrows its name from a person. That person's name is capitalized, therefore the item named after him is likewise capitalized.
Similarly, you would capitalize baked Alaska. Even when the leading b is not capitalized, the A is usually capitalized in print. Also, steak Diane and veal Oscar. In the linked article, the LA Times has chosen not to capitalize veal.
Similarly, the machine gun is referred to as an Uzi submachine-gun rather than Uzi Submachine-Gun. Note the lack of capitalization of the full name of the gun type. The required capitalization is due to attribution to a name.
If Scrabble has chosen to outlaw capitalized words or proper nouns, Uzi fits both bills by default. Uzi as a standalone word is always capitalized as it's a man's name. Uzi when used for a shortened version of Uzi submachine-gun, is not a proper noun, but it's capitalized nonetheless for reasons above.