Littré defines mustard as a condiment made with the seed of Sénevé (or Sinapis) crushed with must, vinegar, or some other liquid. The origin of the word is not completely established. For some, it would be of Celtic origin, and mwstardd in Kymric would mean which emits a strong smell. Others think that the word comes from the Latin mustum meaning must, a mixture obtained by pressing or cooking plants or plant extracts. The term mustard appears as moustarde in Old French, mostade in Walloon, or even moutade in Burgundian.