A superstition — a belief or idea not based on scientific evidence or reason, such as beliefs about luck or omens.
黒猫が前を横切ると不吉だというのは迷信だ。
The idea that a black cat crossing your path is unlucky is a superstition.
迷信に頼らず、根拠のある判断をするべきだ。
You should make reasoned decisions rather than relying on superstitions.
科学が発展するにつれて、古い迷信は減ってきた。
As science has advanced, old superstitions have declined.