radic, radix root eradicate – pull out at the roots; radical – fundamental, looking at things from a drastic point of view; radish – an edible root of the mustard family.

radio radiation, ray radioactive – emitting radiation; radiologist – someone diagnosing or treating via radiation.

ram/i branch ramification – the resulting consequence of a decision; ramify – to spread or branch out; ramus – a branchlike part.

re again, back, backward rebound -to spring back again; rewind – to wind something backward; reaction: a response; recognize: to identify someone or something seen before.

reg guide, rule regent – a person who rules on behalf of a king or queen; regime – a government that rules; regulate – to apply a rule.

retro backward, back retroactive – relating to something in the past; retrogress – to go back to an earlier condition; retrospect – the remembering of past events.

rhin/o nose rhinoceros – a species of animals with a big horn on the snout; rhinoplasty – surgery of the nose; rhinovirus – viruses that are causing the common cold.

rhod/o red rhododendron – a flower with red/pink flowers; rhodium – an element which produces a red solution; rhodopsin – a purple pigment in the retina that is needed for vision.

rid laugh deride – to make fun of someone; ridicule – to make fun or mock; ridiculous – silly, causing laughter.

rrh/ea/oea/ag flow, discharge diarrhea – abnormally excessive bowl movement; hemorrhage – heavy blood flow; catarrh – inflammation of a mucous membrane, especially the nose and throat.

rub red ruby – deep red color and a precious stone of the same color; rubella – measles; bilirubin – reddish pigment in bile.

rupt break, burst bankrupt – unable to pay because you’re “broke”; interrupt – to break into a conversation or event, to disturb; rupture – a break in something.