se·rac also sé·rac 
(sə-răk, sā-)
(sə-răk, sā-)n.
A large pointed mass of ice in a glacier isolated by intersecting crevasses.
[French sérac, strong cheese made from whey, serac (from the resemblance of glaciers with many seracs to unpressed cheese curds ), alteration of French dialectal (Savoy and Switzerland) seraz, sérē, from Vulgar Latin *serāceum, whey cheese, from Latin serum, whey.]