rod vs retinal rod

rod and retinal rod both are nouns.

Word	Noun	Adjective	Verb	Adverb
rod	Yes	No	No	No
retinal rod	Yes	No	No	No

As nouns, rod and retinal rod are synonyms defined as:

rod and retinal rod: a visual receptor cell that is sensitive to dim light

Other synonyms of rod include rod cell.

rod (noun)	retinal rod (noun)
any rod-shaped bacterium	a visual receptor cell that is sensitive to dim light
a long thin implement made of metal or wood
a gangster's pistol
a visual receptor cell that is sensitive to dim light
a linear measure of 16.5 feet
a square rod of land