- Fixation
- Flaccid - see also condition
- Flail
- Flajani (-Basedow) syndrome or disease (exophthalmic goiter) 242.0
- Flap, liver 572.8
- Flare, anterior chamber (aqueous) (eye) 364.04
- Flashback phenomena (drug) (hallucinogenic) 292.89
- Flat
- Flatau-Schilder disease 341.1
- Flattening
- Flatulence 787.3
- Flatus 787.3
- Flax dressers' disease 504
- Flea bite - see Injury, superficial, by site
- Fleischer (-Kayser) ring (corneal pigmentation) 275.1 [371.14]
- Fleischner's disease 732.3
- Fleshy mole 631.8
- Flexibilitas cerea (see also Catalepsy) 300.11
- Flexion
- Flexner's
- Flexner-Boyd dysentery 004.2
- Flexure - see condition