An unlucky number is one widely avoided in at least one major culture:
- Chinese / Japanese / Korean: 4 — sounds like the word for "death" in all three languages. Hospitals and high-rises often skip the 4th floor.
- Western: 13 — Friday the 13th, triskaidekaphobia, hotel floors skipping 13.
- Italian: 17 — Roman numeral XVII is an anagram of VIXI ("I have lived" = dead). Some Italian airlines skip row 17.
- Chinese: 14 ("certain death"), 444 (triple death).
- Christian: 666 (Number of the Beast).
The specific avoidance behavior varies — Western buildings skip floor 13; East Asian ones skip floor 4 (and increasingly 13 too, in international hotels).