すごい

すごい
adjective (i-adjective)
amazing, incredible
1. amazing, incredible, awesome
Expressing that something is impressive, remarkable, or extraordinary. Very commonly used in casual conversation.
Amazing! You're so good at it.
Common exclamation
There are so many people!
Meaning 'a lot' or 'extreme'
あの映画(えいが)すごかった。
That movie was amazing.
She has an incredible talent for languages—apparently she can speak five languages.
What an amazing view!
2. terrible, dreadful
Originally meant something frightening or extreme (can still be used this way).
The typhoon winds were terrible, so we couldn't go outside. Apparently several trees fell over too.
Uses sense 2: terrible/dreadful
The rain is so bad I can't go out.
There was a terrible noise—what was that?
渋滞(じゅうたい)すごかった。
The traffic jam was terrible.
すごい(あつ)
The heat is intense.

すごい conjugates as an i-adjective: すごくない (negative), すごくて (te-form), すごかった (past). The kanji (すご)い can be used but hiragana is more common. In casual speech, すごく is often used as an intensifier meaning 'very' (e.g., すごくおいしい - very delicious). Young people often say すげー as a casual variant.