[Adverbs] 점점 vs. 서서히

점점 and 서서히 both stand for 'gradually'. However, they are not a synonym. 

 

• 점점: 점(漸)+점(漸). 漸 = progress toward a certain direction little by little
• 서서히: 서(徐)+서(徐)+-히(adverbial suffix). 徐 = (go) slowly

 

Therefore, 점점 more focuses on 'little', while 서서히 on 'slow'.

 

When things progress little by little, then they will do so slowly. That's why the two words can be used interchangeably, but the nuance is a bit different.

 

• 우리는 점점 불안해졌다. We grew nervous.
• 우리는 서서히 불안해졌다. We grew nervous.

The first sentence stresses that their anxiety grew bigger and bigger, while the second one emphasizes the fact that they 'slowly' became anxious.