There are multiple definitions:

1. Energy and Vitality Index(English)

   • questionnaire used as measure of positive mental health
   • Mental health, Questionnaire
   • https://doi.org…6/1745-0179-1-9

2. ensemble vector index(English)

   • AF, fECG, EVM, VF
   • Cardiology, Electrophysiology, Pathology
   • https://doi.org…eart.01108.2001

3. enhanced vegetation index(English)

   • a remote sensing metric that measures vegetation greenness, health, and density by reducing atmospheric interference and soil background noise, providing more accurate data than NDVI in dense canopy regions
   • NDVI
   • Environment, Air pollution, Monitoring
   • https://www.geo…au/about-geoai/

4. encoded vector index(English)

   • used to provide fast data access in decision support and query reporting environments
   • SQL
   • Decision making
   • https://www.ibm…-vector-indexes