I don't know how to understand the meaning of "irrational fear". What's "irrational" mean here?

Native speaker’s answer
Rebecca
"Irrational" means "not rational". To explain it with other words, something that is "irrational" cannot be explained with logic or reason. An "irrational fear" means a fear that has no logical reason to exist. Ex: A lot of people have an irrational fear of spiders despite the fact that most spiders can't hurt humans. Ex: My mom is afraid that I won't eat enough when I move out, but I think she's being irrational.