| OC | obstetrical conjugate; occlusocervical; office call; on call; only child; optic chiasma; oral contra... |
|---|---|
| OFD | object-film distance; occipital frontal diameter; oro-facial-digital [syndrome] |
| ofd | object-film distance |
| Rf | in paper or thin-layer chromatography, the distance that a spot of a substance has moved from the po... |
| Rst | in paper or thin layer chromatography, the distance that a spot of a substance has moved, relative t... |