Tomato ketchup or catsup is probably the most American condiment. It does not tip its hat to any of its origins, a Chinese salmon juice or kê-chiap. It probably began as they took the brine from picked fish and made it into a sauce of its own. Eventually non-fish pickles were invented by the English, often with mushrooms. Tomato catsup was a relatively recent variation, and any fish ingredients are long gone.
Similarly, the Chinese hoisin is seafood sauce despite not having any seafood ingredients or history of being used with seafood. The sea and the source is easier to spot in the pasta sauce marinara. It’s from the Latin marinus of the sea which gives us our Marines or mariners. The Italian sauces gets named sailors’ sauce because it kept well on longer voyages or was made to celebrate their homecomings.
Mustard, however, is more true to its roots. The very old condiment was made by mixing crushed seeds and with the mustum, new wine in Latin. Mustum itself was a nickname for vinum mustum, fresh wine. Today you’ll also find mustard made with sour wine or vinager. The Latin was vinum acetum, wine turned sour. The French gave it to us as vinaigre, just as they gave us the salad dressing little vinegar or vinaigrette.
So mustard is short new wine, vinegar short for sour wine.
the journal of gastroetymology 