| Term | Definition |
| ratiocination | reasoning; act of drawing conclusions from premises |
| ravening | rapacious; seeking prey |
| recherche | choice, sought after; rare |
| recondite | abstruse; profound; secret |
| recreant | coward; betrayer of faith |
| recrimination | countercharges |
| recrudescence | reopening of a wound or sore |
| rectitude | uprightness |
| recusant | person who refuses to comply |
| redolent | fragrant; odorous |
| refection | slight refreshment |
| refectory | dining hall |
| refraction | bending of a ray of light |
| refractory | stubborn; unmanageable |
| refulgent | radiant |
| remediable | reparable |
| remonstrate | protest |
| remuneration | compesation; reward |
| rend | split; tear apart |
| repartee | clever reply |
| reprobate | person hardened in sin, devoid of a sense of decency |
| requiem | mass for the dead |
| requite | repay; revenge |
| rescission | abrogation; annulment |
| reticulated | covered with a network; having the appearance of a mesh |
| retrogade | going backwards; degenerating |
| rheumy | pertaining to a discharge from nose and eyes |
| rime | white frost |
| risible | inclined to laugh; ludicrous |
| roan | brown mixed with gray or white |
| rood | crucifix |
| roseate | rosy; optimistic |
| rubicund | having a healthy reddish color |
| ruminant | contemplative; marked with deep thoughts; meditative |
| rusticate | banish to the country; dwell in the country |
| sacerdotal | priestly |
| saffron | orange-colored; colored like the autumn crocus |
| sagacious | keen; shrewd |
| saltatory | relating to leaping |
| salubrious | healthful |
| salutary | tending to improve; beneficial; wholesome |
| salver | tray |
| sangfroid | coolness in a trying situation |
| sanguinary | bloody |
| sanguine | cheerful; hopeful |
| sapid | savory; tasty |
| sapient | wise; shrewd |
| sartorial | pertaining to tailors |
| satiety | condition of being crammed full; glutted state; repletion |
| satrap | petty ruler working for a superior despot |
| saturnine | gloomy |
| savant | scholar |
| scarify | make sleight incisions in; scratch |
| scintilla | shred; least bit |
| sciolism | quackery; superficial information |
| scour | to clean by hard rubbing; to clean using a detergent or other harsh agent |
| scrappy | disconnected; fragmented |
| screed | long, tiresome language |
| scullion | menial kitchen worker |
| sebaceous | oily; fatty |
| sedentary | requiring sitting |
| sedulous | diligent |
| seine | net for catching fish |
| senescence | state of growing old |
| sententious | terse; concise; aphoristic |
| septic | putrid; producing putrefaction |
| sepulcher | tomb |
| sequacious | eager to follow; ductile; proceeding smoothly; happening regularly; something that is disposed to follow. |
| seraph | high-ranking, six-winged angel |
| serpentine | winding; twisting |
| serried | standing shoulder to shoulder; crowded |
| shambles | slaughterhouse; scene of carnage |
| shibboleth | watchword; slogan |
| shoal | shallow place |
| shunt | to move; to shove; to get rid of or send away; to change the course of |
| sibylline | prophetic; oracular |
| sidereal | relating to the stars |
| similitude | similarity; using comparisons such as similes |
| sinecure | well-paid position with little responsibility |
| sinuous | winding; bending in and out; not morally honest |
| sirocco | warm, sultry wind blown from Africa to southern Europe |
| slake | quench; sate |
| slattern | untidy or slovenly person |
| sleight | dexterity |
| sluice | artificial channel for directing or controlling the flow of water |
| solecism | a nonstandard or outdated grammatical construction |
| solicitous | worried; concerned |
| solstice | point at which the sun is farthest from the equator |
| somatic | pertaining to the body; physical |
| somnambulist | sleepwalker |
| somnolent | half asleep |
| soporific | sleep producer |
| soupcon | suggestion; hint; taste |
| spangle | small metallic piece sewn into clothing for ornamentation |
| specious | seemingly reasonable but incorrect |
| splenetic | spiteful; irritable; peevish |
| spoliation | pillaging; depredation |
| spoonerism | accidental transposition of sounds in successive words |
| sportive | playful |
| spume | froth; foam |
| stanch | check flow of blood |
| stentorian | extremely loud |
| stertorous | having a snoring sound |