Sugoku
 

I noticed this is a word I hear frequently in Japanese.
Yet I haven't found it in JWPce or NJStar or any online dictionary I've used.

What does it mean?

It means "very."

Ah, thanks a million! And such quick help too.:)

Its just すごい (sugoi) in a different form. I usually see sugoku used more in writing, while sugoi is used more in speech. Sugoi is a bit more casual and used by younger Japanese, whereas sugoku is a bit more formal.

すごい changing to すごく is just like 早い (はやい, quick) changing to 早く（はやく, quickly）. By itself, すごい means amazing or brilliant, and by changing the い to a く, it is just like adding "ly" to the end of the word in English to make amazingly, or brilliantly, or more casually, "very", like Harold said.