Od n. : An alleged force or natural power, supposed, by Reichenbach and others, to produce the phenomena of mesmerism, and to be developed by various agencies, as by magnets, heat, light, chemical or vital action, etc.; -- called also odyle or the odylic force.

Example:
What would cause an Od reading at 600 nm to reflect a decrease in the number of cells?

Taxonomy
OD, free encyclopedia, language, Norse god, commonly used, omne, industrial band, pupil, meanings, Oad, Oculus dexter, left eye, search, two letter abbreviation, medicine, Basic science, life force, replacement.

Defination from the web:
OD and OS, these are most commonly used in ophthalmology and optometry. ... Once daily, a schedule for giving medication or other treatment, i.e. once per day (originally from the Latin omne in die) ...