Definition:
The word "supposedly" is an adverb that means something is believed or thought to be true, but it might not actually be the case. It is often used when we talk about what people think or say, rather than what is definitely true.
Common Usage:
"He is supposedly the best player on the team."
(This means that people believe he is the best, but it may not be true.)
Expressing Doubt:
"The movie is supposedly scary, but I didn’t find it frightening at all."
(Here, you are saying that others think the movie is scary, but you disagree.)
In summary, "supposedly" is a useful word to express what people think is true but may not be.