Muesli is a type of breakfast cereal made from a combination of grains, nuts, and dried fruits. The two crossword solutions for the term 'Muesli Ingredient' are OAT and OATS. OAT is a 3-letter word that stands for 'Old-fashioned Avena sativa, ' which is a type of cereal grain. OATS is a 4-letter word that stands for 'Organic Avena sativa, ' which is a type of cereal grain that is grown without the use of synthetic fertilizers or pesticides. Both OAT and OATS are common ingredients in muesli.