- The Riemann zeta function or Euler–Riemann zeta function, denoted by the Greek letter ζ (zeta), is a mathematical function of a complex variable
- Index, Washington (Wikipedia)
Index (Lushootseed: x̌əx̌aʔusalʔtxʷ) is a town in Snohomish County, Washington, United States. The population was 178 at the 2010 census.