Adjectives that begin with the letter R are listed in this post.
rabbinical, rabid, racial, racist, racy, radiant, radical, radioactive, ragged, raggedly, rainy, rambunctious, rampant, ramshackle, random, rank-and-file, ranking, rapid, rapid-fire, rare, rarer, rational, raucous, raw, razor-thin
reactionary, read-only, ready, ready-to-wear, real, realistic, reality-based, real-life, real-time, real-world, rear, reasonable, reassuring, rebellious, recalcitrant, recent, receptive, recessionary, recession-proof, rechargeable, reciprocal, reckless, reclusive, recognizable, recombinant, recommended, reconstructed, record, record-breaking, record-tying, recreational, rectangular, recurrent, recut, red, red-and-white, reddish, redeemable, red-faced, red-handed, redone, redrawn, redundant, reedy, re-evaluate, refined, reflective, reflex, reformed, reformer, reform-minded, refreshing, refrigerated, refundable, regional, regressive, regrettable, regular, regular-season, regulatory, relative, relentless, relevant, reliable, reliant, religious, reluctant, remarkable, remedial, reminiscent, remiss, remote, remote-controlled, removable, renewable, renowned, rental, rented, repayable, repeated, repellent, repentant, repetitious, repetitive, replete, repossessed, representational, representative, repressive, reproducible, reproductive, reptilian, republican, repulsive, reputable, requisite, resentful, resident, residential, residual, resilient, resistant, resonant, resounding, resourceful, respectable, respectful, respective, respiratory, resplendent, responsible, responsive, re-starting, restive, restless, restocking, restorative, restrained, restrictive, resurgent, retail, retaliatory, retarded, reticent, retinal, retired, retractable, retro, retroactive, revered, reverential, reverse, reversible, reviled, revitalization, revolting, revolutionary, rewarding
ribbed, rich, richer, richest, richter, rickety, riddled, ridiculous, rife, right, righteous, rightful, right-hand, right-hander, right-to-life, rightward, right-wing, rigid, rigorous, ripe, rip-roaring, risk-averse, risk-free, riskier, riskiest, risky, ritzy, rival, riveting
roadside, roasted, robotic, robust, rocket-propelled, rock-hard, rocky, rogue, roman, romanesque, romantic, rome-based, roomy, rosier, rosy, rotary, rote, rotten, rough, rough-and-tumble, rough-cut, rougher, roughest, rough-hewn, round, round-table, round-the-clock, round-the-world, round-trip, routine, rowdy, royal
rude, rudimentary, rueful, rugged, ruinous, rump, rumpled, runaway, run-down, run-of-the-mill, rural, rush-hour, russian, russian-language, rustic, rusting, rusty, ruthless