If someone is superstitious, they believe in things that are not based on reason or scientific evidence, like thinking that certain actions or things can bring good or bad luck.
Being superstitious can be seen as silly or irrational by some people.
Examples:
She is superstitious and thinks that breaking a mirror brings bad luck.
Some people are superstitious and think that a black cat crossing their path brings bad luck.
He is superstitious and believes that wearing a certain shirt brings good luck.
I am not superstitious, but I still knock on wood sometimes.
My grandma is superstitious and thinks that spilling salt brings bad luck for the whole day.
The old man is superstitious and always carries a rabbit's foot for good luck.