Gingivitis. gumboil. The white lump on your gums is probably not gingivitis. It can be related to a dead tooth, which might require root canal treatment, a small piece of bone that is protruding through the gum, or just a variation of normal. Gingivitis looks like red, irritated gums around the teeth, and is a result of bacteria which is not removed by proper brushing (or not brushing). Please see your dentist.
Gingivitis. Gingivitis does not manifest itself as a "white lump" on the gums. Gingivitis by definition is inflammation of the gum tissue without resultant loss of the bone or attachment apparatus that holds the teeth in the jaw. White lumps are usually indicative of some other type of problem likely most commonly a response to local irritation, but it is always advisable to have it checked out asap.