Gesundheit was borrowed from German, where it literally means "health"; it was formed by a combination of gesund ("healthy") and -heit ("-hood"). Wishing a person good health when they sneezed was traditionally believed to forestall the illness that a sneeze often portends.

What does gesundheit mean slang?

interjection. (used to wish good health, especially to a person who has just sneezed.)

Is it illegal to say gesundheit?

So the truth is that such a rule really did exist. In Iowa (and perhaps elsewhere in the United States and abroad), it was illegal to say Gesundheit in public or on the telephone - just as it was illegal to say. Or French, or Spanish.