Just a random question folks.

Does anyone have any theories about why Longsword is one word, but every other kind of sword is two words?

That's an interesting question, and as someone obsessed with etymology, I am not sure I will rest until I find the answer. (Not kidding.)

I'll let you know if I turn up anything.

It is not a long sword but a longsword, a rather specific european sword I think.

That is true, but I'm not sure it solves the riddle. If the long sword is a longsword, why isn't the short sword a shortsword, and the broad sword a broadsword?

I have only spent 10 minutes researching the matter so far, but I will put in hours if I have to. Either to  find the answer or else admit defeat knowing I did my best.

But Narjan, if you can find it first, by all means please feel free to do so and then share the info. (Same goes with anyone else on here who may just happen to know the answer off the top of their head.)

Near as I can tell, the AD&D Longsword is a gygaxianism. The German Langenschwert was intended for two hand use, being "longer" than other swords. Add in that the term "Broadsword" is closer to being a modern term than it is a medieval one (apparently first used in descriptions in 19th century collections) and we find the Gygaxian nomenclature probably had more to do with fantasy than fact.

This is not a complaint against the system. I would much rather write Broadsword or Longsword than scramanseaxe on a character sheet. Granted, Bastard Sword is the "original" name for Reahlyn's blade--a sword neither in the one-handed nor two-handed "families".

https://www.thearma.org/SwordForms.html Has excellent information.

Well, in fact I've also seen written as one word broadsword and shortsword, while I've never seen as a single word the bastard or two handed...

If so, it might just be a matter of the adjective length, with one sillabe being added to the word, while more than this being kept separated.

Just a speculation though...