Yes, teff is gluten-free.
Teff, also called Williams lovegrass, Wilman lovegrass or annual bunch grass, is a plant native to east-central Africa. It has tiny, edible seeds, ranging in color from white to a red-brown. Because teff was domesticated over 6,000 years ago, it is often called an ancient grain.
Teff can be cooked by boiling it in water. The teff seed is so small that it cooks much faster than other grains, often in half the time. When ground into a fine flour, teff has a nutty taste suitable for pie crusts, pancakes, scones and shortbreads. It is the main ingredient in injera, a traditional Ethiopian flatbread. Teff seeds can also be used to make alcohol.
Teff is especially high in fiber and vitamin C, which is unique for a grain and makes it a great addition to any gluten-free diet! However, you should still read the ingredients list on any teff product you buy to verify that no gluten-containing ingredients were added.