A dreadful thing or experience is extremely unpleasant and frightening.
Imagine watching a scary movie that's so intense it makes your skin crawl - that's what people might mean by "dreadful". When someone describes an event, situation, or even a person as dreadful, they're usually implying that it's not just bad, but really, really awful. It's the kind of experience that you wouldn't wish on anyone else, and it might even leave you with some lasting fear or anxiety.
It can also mean something that's in poor condition, broken down, or worn out - like a dreadful old car that needs to be junked. In this case, "dreadful" emphasizes how bad the thing is, often beyond repair.
Full of something causing dread, whether
