- First degree atrioventricular block
- First generation antipsychotics
- First impression
- First metacarpal bone
- First metatarsal bone
- First molar
- First order reaction
- First pass effect
- First responders
- First rib resection
- First-in-class medication
- Fisetin
- Fish allergy
- Fish liver oils
- Fish meat
- Fish oil
- Fish oils
- Fish protein
- Fish-eye disease
- Fisher exact test
- Fisher information
- Fisher's method
- Fission products
- Fissured tongue
- Fistulas
- Fistulectomy
- Fistulotomy
- Fitness culture
- Fitness landscape
- Fitness to Practise
- Fitz-Hugh-Curtis syndrome
- Fitzpatrick scale
- Five factor model
- Five stages of grief
- Five-number summary
- Five-year survival rate
- Fixation
- Fixation disparity
- Fixation index
- Fixed drug eruption
- Fixed partial denture
- Fixed prosthodontics
- Fixed-dose procedure
- Flaccid dysarthria
- Flaccid paralysis
- Flag tag
- Flagella
- Flagellates
- Flagellin
- Flail chest
- Flail limb
- Flame test
- Flank
- Flank pain
- Flap endonuclease
- Flap surgery
- Flapping tremor
- Flash freezing
- Flash pulmonary edema
- Flashbacks
- Flashbulb memory
- Flat bones
- Flat feet
- Flat-panel detector
- Flatfoot
- Flattening the curve
- Flatulence
- Flavanols
- Flavanones
- Flavin
- Flavin mononucleotide
- Flavin reductase
- Flavin-containing monooxygenase
- Flavin-containing monooxygenase 3
- Flavins
- Flaviviridae
- Flavivirus
- Flavobacterium
- Flavocoxid
- Flavodoxin
- Flavokavain
- Flavokavain A
- Flavone
- Flavones
- Flavonoid biosynthesis
- Flavonoids
- Flavonolignan
- Flavonols
- Flavoproteins
- Flavored syrup
- Flavoring agent
- Flavoxate
- Flax
- Flecainide
- Fleischer ring
- Fleiss' kappa
- Flemingia
- Fleroxacin
- Flesh
- Flexibility
- Flexible electronics
- Flexion point
- Flexner Report
- Flexner Wintersteiner rosette
- Flexor carpi radialis
- Flexor carpi ulnaris
- Flexor carpi ulnaris muscle
- Flexor digitorum brevis
- Flexor digitorum brevis muscle
- Flexor digitorum longus
- Flexor digitorum longus muscle
- Flexor digitorum profundus
- Flexor digitorum profundus muscle
- Flexor digitorum superficialis
- Flexor digitorum superficialis muscle
- Flexor hallucis brevis
- Flexor hallucis longus
- Flexor hallucis longus muscle
- Flexor muscle
- Flexor pollicis brevis
- Flexor pollicis longus
- Flexor reflex
- Flexor retinaculum
- Flibanserin
- Flicker
- Flicker fusion threshold
- Flight zone
- Flip angle
- Flippase
- Flipper
- Flo
- Floaters
- Floc
- Flocculants
- Flocculation
- Flocculonodular lobe
- Flocculus
- Flock house virus
- Floor effect
- Floor of mouth
- Floppy eyelid syndrome
- Florbetapir
- Florfenicol
- Flour
- Flourishing
- Flow cytometry
- Flow diverter
- Flow focusing
- Flow injection analysis
- Flow-FISH