Stupendously is the adverb of stupendous. It does not usually describe how an action is done; instead it sits in front of an adjective and means 'to a surprisingly great degree' — stupendously rich, stupendously boring, stupendously successful, stupendously expensive. Think of it as a bigger, more dramatic 'very'. Two things are worth noticing about how people actually use it. First, it pairs freely with negative adjectives as well as positive ones: 'stupendously wrong', 'stupendously bad'. When it does, the speaker is usually being wry — the wrongness was so complete it deserves applause. Second, because the word sounds grand, writers often use it for comic exaggeration, especially in reviews and columns: 'a stupendously silly film'. It can also modify a verb in the older, more literal way ('the business grew stupendously'), but this is less common now and sounds formal. In speech, most people would reach for 'incredibly' or 'unbelievably' instead; 'stupendously' carries a hint of a raised eyebrow.

驚人地、極其地（語氣誇張，常帶一點調侃）