sýrður
Sýrður is an Icelandic adjective meaning “sour” or “acidic.” It is commonly used to describe the taste or chemical character of substances, especially foods and drinks that have become acidified or fermented. In Icelandic culinary vocabulary it appears in familiar terms such as súrmjólk, the sour milk/yogurt drink, and sýrður rjómi, sour cream, where the word helps convey the sour quality of the product.
Etymology and related forms trace sýrður to the verb sýra, “to sour,” which itself comes from Old
Grammar and usage notes: sýrður is an inflecting adjective and must agree with the noun it modifies
See also: súr (shorter form meaning sour in some contexts), súrmjólk (sour milk), sýrður rjómi (sour cream).