There are multiple definitions:

1. fourth ventricle outlet obstruction(English)

   • a rare cause of obstructive hydrocephalus
   • CSF, CT, DWM, ICP, ETV
   • Brain (dys)function, Headache
   • https://doi.org…0064-015-1368-x

2. functional virgin olive oil(English)

   • OOPC, AEES, HDL, LCAT, FVOO, FVOOT, LDL, OO, PC, PON, VOO
   • Nutrition, Metabolism
   • https://doi.org…/mnfr.201500030