The phrase "egg substitute" refers to a product that can be used instead of eggs in recipes. It is made to mimic the functionality and sometimes the taste of eggs, but does not come from an actual egg. Full definition
See, I know I've mentioned this before, but one of the advantages of vegan baking is in the ingredients you end up using as egg substitutes. (connoisseurusveg.com)
He used vegan egg substitute for recipes that needed «glue». (chowvegan.com)