When searching for hypoallergenic wet cat foods often I see single protein foods appearing in the results, which don't feature the term "hypoallergenic". I wonder if this is a design flaw in such sites use of "synonym" search terms (grouping anything that's a special diet together), or if the terms are genuinely synonyms.
The term 'hypoallergenic' is a marketing strategy. If a cat is really allergic to many proteins the best would be a single protein food without any dairy, grains, potatoes, sugar ... And then feed only that for a time before deciding if the cat can tolerate this protein.
Just because the food label says: hypoallergenic, does not mean that the content is really healthy or has low amount allergy risky content. Some companies just use nice labels like that to get people to buy their low quality food. (I don't say all of them do, but better look at the contents of the food than at the name !)
HYPOALLERGENIC DIETS FOR DOGS AND CATS ARE GAINING POPULARITY, AND DO OFFER SOME HEALTH BENEFITS, but some of the marketing hype can mislead pet owners because pet food allergies are entirely specific to the individual pet.
A food that is ‘hypo-allergenic’ for one pet may still trigger reactions in others, and sometimes additional measures are needed to unearth the true cause.
Since different pets are allergic to different ingredients, there obviously can be no such thing as a food that is hypo-allergenic or non-allergic for every pet on the planet!
The key is to find out what ingredients your individual pet can and cannot tolerate, and choose or make his food accordingly.