Triskaidekaphobia is the term for the fear of the number 13.
The word combines Greek roots: “treiskaideka,” meaning thirteen, and “phobos,” meaning fear. It describes anxiety or avoidance associated with 13, especially when the number appears in dates, addresses, rooms, or floors of buildings.
The superstition has influenced architecture and everyday design. Some hotels and office buildings skip the 13th floor, labeling it 14 or 12A instead. This does not mean the floor is physically absent; the numbering is changed to reassure visitors or tenants.
Triskaidekaphobia is different from paraskevidekatriaphobia, the more specific fear of Friday the 13th. The number 13 has acquired unlucky associations in several traditions, but those beliefs are cultural rather than evidence that the number itself causes harm. The term was documented in psychological writing by 1910.