1Used to emphasize that something is extreme in degree or amount — a stronger, more emphatic version of "very" or "incredibly," often said with a sense of awe. Usually written in kana.
昨日のライブはものすごい人気で、チケットがすぐ売り切れた。
Yesterday's live show was tremendously popular, and the tickets sold out immediately.
このカレーは辛さがものすごいから、覚悟して食べてね。
This curry is incredibly spicy, so be prepared before you eat it.
彼女はものすごいスピードで問題を解いていった。
She solved the problems at an incredible speed.
今年の夏はものすごい暑さが続いている。
This summer the tremendous heat has been continuing.
2Used to describe something as frighteningly or unpleasantly intense — emphasizing a ghastly, horrific, or hard-to-look-at quality.
台風で倒れた木々のものすごい光景に息をのんだ。
I gasped at the horrific sight of the trees knocked down by the typhoon.
彼はものすごい形相でこちらをにらんでいた。
He glared at us with a frightful expression on his face.
事故の現場はものすごくて、見た人はみんな声を失った。
The scene of the accident was so ghastly that everyone who saw it was left speechless.