Humongous means very, very big — not a real measured size, but a feeling of size. People say it when they want the thing to sound almost too big, and a little funny: a humongous pizza, a humongous bag, a humongous problem. It is casual talk, often from young people or in jokes. You would not put it in a serious report or a careful school essay; huge or enormous belongs there. It is American in feel, though many people outside the US use it now. Though actually, speakers do not agree on how much bigger than huge it is — it is just extra stress, not a step on a ruler.

超大的、巨大無比的（口語、帶誇張；不像 enormous 那樣正式）