| MORD | magnetic optical rotatory dispersion |
|---|---|
| OCR | oculocardiac reflex; oculocerebrorenal [syndrome]; optical character recognition |
| OD | Doctor of Optometry; obtained absorbance; occipital dysplasia; occupational dermatitis; occupational... |
| ODU | optical density unit |
| OES | oral esophageal stethoscope; optical emission spectroscopy |