"Plain flour" refers to a type of flour that does not have any extra ingredients or rising agents added to it. It is a basic flour often used for everyday cooking and baking. Full definition
It's fabulous to find a cake recipe using only one - third cup of sugar, 1 cup plain flour and 50 grams of butter that tastes sensational with lots of fruit. (bbcgoodfood.com)
Can I use plain flour with some normal ground almonds combination? (deliciouslyella.com)
Instead of white bread, mix a cup of whole wheat flour with 2 cups of plain flour, or add rye. (cookingninja.com)