quad : four
quadrant (each of four parts of a plane or area)
quadrangle (a square or rectangle, quad)
quad (a rectangular space or courtyard enclosed by buildings)
quadruped (an animal that has four feet)
quart : fourth
quarter (one fourth; to divide into four parts; to range over in all directions, patrol)
quart (a fourth of a gallon)
quartet (a musical composition or group involving four voices or instruments)
qual :characteristic
qualify (to become eligible for a competition)
qualitative (relating to the quality of something rather than its quantity)
quality (the degree of excellence of something)
quant : amount
quantify (to express or measure the quantity of)
quantity (an amount)
quantum (a required or allowed amount, the smallest needed amount)
quasi : partly, so called
quasi- (seemingly; apparently but not really)
quasar (quasi-stellar (astronomical object))
quer, quir, ques : seek
conquer (to overcome and take control of
inquire (to ask for information from someone)
query (a question, especially one addressed to an official)
querulous (complaining in a petulant or whining manner)
quest (a long or arduous search for something)
request (an act of asking politely or formally for something)
quota : amount, how many
quota (a fixed share of something that a person or group is entitled to)
quotient (a result obtained by division, an amount of a specified quality)
quotidian (occurring every day, daily)
quint : five, fifth
quintessence (pure essence, mythical fifth element)
quintuple (fivefold)
R
radic : root
eradicate (pull out at the roots → eliminate)
radical (thorough going, fundamental; revolutionary, drastic)
radish (an edible root of the mustard family)
ranc : stink
rancid (smelling or tasting unpleasant as a result of being old and stale)
rancor (hate, bitterness or resentfulness)
rancorous (characterized by bitterness or resentment)
rap, rapi, rapt : plunder, seize
rapacious (aggressively greedy or grasping)
ravish (fill someone with intense delight; enrapture)
rapine (the violent seizure of someone's property)
rapture (a feeling or expression of intense pleasure or joy)
surreptitious (being kept secret, stealthy, secretive)
ras, raz : scrape
abrasive (showing little concern for the feelings of others, caustic, biting)
rasp (a harsh, grating noise, a tool for scraping)
razor (a tool to remove hair)
rect : right, straight
erect (rigidly upright or straight; to construct a building)
direct (shrotest, quickest, straightforward)
rectangle (a plane figure with four straight sides and four right angles)
rectify (to put right; correct, amend, reform, make good)
reg, rect : rule
regime (government, authority)
regent (a member of the governing body)
insurrection (a violent uprising against an authority, insurgence, mutiny, revolt)
regal (fit for a king, being magnificent or dignified)
regulate (to control or supervise something)
relic : to leave, neglect
relic (an object surviving from an earlier time, antique, heirloom)
derelict (in a very poor condition from disuse, dilapidated; abandoned property)
dereliction (the shameful failure to fulfill one's obligations, negligence)
resid : remain
reside (to have one's permanent home in a particular place)
residence (a person’s home)
residual (remaining after the greater part or quantity has gone)
residue (a small amount of something that remains)
rhino : nose
rhinoceros (animal species with a big horn on the snout)
rhinoplasty (surgery of the nose)
rhinovirus (viruses that cause the common cold)
rhod(o) (red, rose)
rhododendron (a type of flower)
rhodolite (a pale violet or red variety of garnet, used as a gemstone)
ridi, risi, ri : laugh
deride (to make fun of someone)
ridicule (to make fun or mock)
ridiculous (silly, causing laughter)
risible (laughable, comical)
rig : stiff
rigid (unable to bend, not able to be changed or adapted)
rigor (severity, strictness)
rigorous (extremely thorough, exhaustive, or accurate)
roga : ask, beg
abrogate (to repeal, overturn; to evade a responsibility or duty)
derogatory (showing disrespectful attitude, belittling, disparaging)
interrogate (to ask questions aggressively)
supererogation (the performance of more work than duty requires)
rota : wheel
rotary (revolving around a center or axis; a rotary machine)
rotate (to move in a circle)
rotisserie (cooking tool to roast meat)
rrhea : flow, discharge
diarrhea (abnormally excessive bowel movement)
hemorrhage (heavy blood flow)
catarrh (inflammation of a mucous membrane, especially the nose and throat)
rub (red)
rubella (a type of disease where skin becomes reddish)
rubric (a heading on a document originally written in red)
ruby (a red gemstone)
rupt : break, burst
abrupt (sudden and unexpected)
disrupt (to interrupt)
bankrupt (being unable to pay back debt, a bankrupt person)
interrupt (to break into a conversation or event, to disturb)
rupture (to break, to breach, a break)