There are multiple definitions:

1. fatal familial insomnia(English)

   • PRNP, CJD, GSS, FI
   • Sleep medicine
   • https://doi.org…0038-004-0150-7

2. Five-Factor Inventory(English)

   • CFA, CSR, GAD, MDD, NEO, NEO-FFI, OCD, PCA, PI, SOC, FFM
   • Psychology
   • https://doi.org…073191110382848

3. Fried Frailty Index(English)

   • frailty is strongly associated with cognitive impairment, depressive mood, and malnutrition in some community-dwelling elderly populations
   • FRAIL, CGA, FI
   • Frailty, Cognitive function, Depression, Nutrition
   • https://doi.org…0520-015-0337-0