Is frightening a synonym to awful?

Not exactly. "Frightening" and "awful" are both negative words, but they describe different things:

* Frightening describes something that causes fear or alarm. It emphasizes the emotional response of fear.

* Awful describes something very bad or unpleasant. It's a broader term, encompassing not just fear, but also disgust, sadness, or simply a very negative experience.

Here's an example:

* Frightening: A scary movie is *frightening* because it makes you feel scared.

* Awful: A bad accident is *awful* because it's a terrible tragedy.

While a frightening experience can be awful, not all awful experiences are frightening.

Think of it this way: "Frightening" is a subset of "awful."