[jimswhims]

Think it comes from the german word for salmon, "Lachs", or at least an earlier version of the word.

[unwind]

Swedish is even closer, there it's "lax" [1].

[1]: https://en.wikipedia.org/wiki/Gravlax

[miramba]

I learned about „lox“ in NYC, a native told me it comes from jiddish, which is kind of a german dialect.