| FFD | Fellow in the Faculty of Dentistry; focus-film distance |
|---|---|
| FOD | focus-to-object distance; free of disease |
| FSD | focus-skin distance |
| HD | Haab-Dimmer [syndrome]; Hajna-Damon [broth]; Hansen disease; hearing distance; heart disease; helix ... |
| HDLW | distance from which a watch ticking is heard by left ear |