Tessarakontaphobia, also known as Quadragintaphobia , is the fear of the number 40. It is mainly feared in Ukraine, where 40 years is the only date that is not celebrated in Ukraine, especially for men. The negative association with the number 40 stems from its connection to death and mourning in both folk tradition and Eastern Orthodox Christian practices.
It is also feared in China because it contains the digit "4," which sounds like the word for "death". This association with death is so strong that entire floors or numbers containing the digit 4, such as floors 40-49, are often omitted in buildings, similar to how the number 13 is avoided in Western cultures.