There are multiple definitions:

1. fast orthogonal search(English)

   • a signal processing tool providing high-resolution spectral estimation, and a general purpose nonlinear modeling technique that finds functional expansions using an arbitrary set of nonorthogonal candidate functions
   • FFT, SNR
   • Signal analysis, Model(ing), Nonlinear analysis/system
   • https://doi.org…0158-011-0695-y

2. Fos proto-oncogene, AP-1 transcription factor Subunit(English)

   • transcription factor that plays an important role in many cellular functions and has been found to be overexpressed in a variety of cancers
   • FBJ
   • Genetics, Hematology, Oncology, Transcription
   • http://atlasgen…nes/GC_FOS.html

3. Framingham Offspring Study(English)

   • undertaken to expand upon knowledge of cardiovascular disease, particularly in the area of familial clustering of the disease and its risk factors
   • FHS, FOF
   • Epidemiology, Cardiology, Risk factor
   • https://doi.org…als.aje.a112813

4. fructo-oligosaccharide(English)

   • as reference for wheat bran-derived arabinoxylooligosaccharides
   • AcAGX, avDAS, AXOS, SCFA, XOS, AcGGM
   • Nutrition
   • https://doi.org…5/jn.108.094367
   • https://doi.org…Sphere.00554-18

5. first order statistic(English)

   • FTF
   • Statistics
   • https://doi.org…859-022-05059-1