Tetraphobia

Tetraphobia is fear of or avoidance of the number four, especially where its pronunciation resembles a word for death. It can shape naming, design, and everyday choices.

Elevator floor numbering: The system used to label levels served by an elevator. Some buildings omit floor numbers containing four to accommodate tetraphobic preferences.
Chinese numerology: A tradition interpreting numbers through their sounds, associations, and cultural meanings in Chinese-speaking communities. It gives four an ominous association through its resemblance to the word for death.
Triskaidekaphobia: Fear of or avoidance of the number thirteen. It is a comparable number-specific aversion associated with different cultural traditions.
Tetraphobia in China: Avoidance of the number four in Chinese cultural and commercial settings. Chinese-language sound associations provide a prominent setting for the practice.
Room numbering: A system for assigning identifiers to rooms within a building. Hotels and hospitals may skip room 4 or numbers containing four.
Homophony: The linguistic relation between words that sound alike but have different meanings. A sound resemblance, rather than the numeral itself, underlies many forms of tetraphobia.
Superstition: A belief or practice linking events or objects to outcomes without established causal evidence. Avoiding four often reflects shared beliefs about luck or danger rather than clinical phobia.
Tetraphobia in Japan: Avoidance of four in Japanese settings, often linked to the reading shi. Japanese readings of four connect the practice to a distinct local linguistic context.
Product naming: The practice of choosing names and model identifiers for goods. Manufacturers sometimes avoid model numbers containing four in markets where it is considered unlucky.
Chinese language: A group of related Sinitic languages, including Mandarin and Cantonese. In Mandarin, sì (four) sounds similar to sǐ (death), though tones distinguish them.

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