to mix food {esp. flour, egg whites} into another food mixture by turning it carefully with a spoon so that there is air in the mixture
Beat the eggs and butter, then fold in the flour.
phrasefold in fold in sth • fold sth in • fold sth into sth to gently mix a food into a mixture when you are cooking: Beat the egg whites and fold them into the batter just before baking.Make sure that you fold in the cream before adding the fruit.■ SIMILAR TO: mix in/into