Quadrimum: best or oldest wine; four-year-old wine [from L. quad (“four”) + -mus]
Quaintise: a cunning little ploy or strategem; craft; elegance [from Fr. cointise]
Qued: bad; evil [from Proto-Wt Germanic. kwād (“bad”; “evil”)]
Quillet: a subtlety in argument; a subtle distinction [Uncertain, poss from L. quidlibet (“anything”)]
Quinquagesima: pertaining to 50 days [from L. quinquaginta (“fifty”)]
Quisquous: hard to deal with; dubious; of people: having a character difficult to assess [from Scot. Eng. from L. quisquis (“whosoever”)]
Quodlibet: a philosophical or theological point proposed for disputation; a whimsical combination of familiar melodies or texts [from L. qui (“what”) + -libet (“it pleases)”]
Quondam: that once was; (a) former [as that grand dame of words Merriam Webster says: “Looking for an unusual and creative way to say “former”?” Quondam (which came to English in the 16th century from Latin quondam, meaning “at one time” or “formerly”) ~ look no further!]
Rampallian: a bold, forward, rampant or wanton woman [Elizabethan term, Henry IV Pt II, Act II)
Rasorial: habitually scratching the ground in search of food [from LateLat. rasor (“one that scrapes”) + -ial]
Recusant: refusing staunchly to comply with some generally accepted rule or custom (Orig. Relig.) [from L. re- + causari (“to give a reason”), from causa (“cause”; “reason”)]
Redivivus: restored to life, or to full liveliness; reborn [L. “reused”]
Remiped: (Zool.) having feet that are adaptable as oars [from L. remiped-, remipes (“oar-footed”)] 👣
Remontado: someone who has fled to the mountains or hills and renounced civilisation; a Northern Philippine’s tribesman; go-back (to the wild) [Galician (Sp.). remontado/remontada]
Renable: eloquent; fluent [from OldFr. resnable]
Resipiscence: recognising one’s own error or errors; to see reason once again [from L. resipīscere (“to regain consciousness, come to one’s senses”)]
Resupinate: (Botany.) upside down as a result of twisting ; (Medic.) lying on the back [from re + L. –supīnus, from sup- sub (“under”)]
Rhonchisonant: making a snorting noise; snorting [from L. rhonchus, + –sonans]
Rixation: quarrelling [from L. rīxārī (“to quarrel”)]
Roinous: mean, nasty and contemptible (origin unknown, possibly from Fr)
Rodomontade: empty boasting and blustering; arrogant ranting; braggadocio [from Rodomont, a character in Ariosto’s Orlando Furioso]
Ruptuary: one not of noble blood; a plebeian; a commoner; a roturier [from MidFr. roturier]
RESILE: it was a toss-up whether to include ‘resile’ in the R supplement or not. It’s an automatic go-to word politicians and civil servants reach for (ie, “I WON’T resile from…”) whenever they feel the need to strongly defend an unpopular or controversial decision. Thus it’s become a bit of a cliche 🔜 Resile, meaning to abandon a position or course of action OR to return to a prior position.
Is the Latin “rara avis” sufficiently in English usage to qualify? Lit. meaning = “rare bird”. A rarity; a person or thing which is rare or unique, uncommon or unusual, outstanding or exceptional.
I’ll raise you Ratiocination:
forming judgements by a process of logic and reason the process of exact thinking : reasoning. A reasoned train of thought.
(from L ratio = reason)
Edgar Allan Poe is said to have called the 1841 story “The Murders in the Rue Morgue” his first “tale of ratiocination.”