The Rabbinical Assembly's Pesah Guide indicates that "most Ashkenzic authorities define kitniyot (kitniot, kitniyos, kitnios) to include rice, corn, millet, legumes (beans and peas; however string beans are permitted....  Peanuts and peanut oil are permissible.  Some Ashkenazic authorities permit, while others forbid, the use of legumes in a form other than their natural state, for example, corn sweeteners, corn oil, soy oil,  Sephardic authorities permit the use of all of the above.  Consult your rabbi for guidance in the use of these products."

Some Orthodox rabbis have a more extensive list of kitniyot.

Rabbi Dick Israel, z"l once said: "In general, kitniyot are those small (kitniyot - from katan) seeds or beans which look a little like grains and which need to be cooked to be eaten. Though frequently translated as legumes, aside from peas and peanuts, they are NOT legumes. And some legumes, like alfalfa leaves which can be used for salad, ARE NOT kitniyot. Legumes are plants whose root nodules make nitrogen. Since "teensy-weensies" or "tinies" are not translations that are very likely to make it into ordinary English parlance, the most appropriate translation for kitniot, it seems to me, is kitniot."