1 letter:
.

2 letters:
ca, cl, ga, li, no, os, pu

3 letters:
age, day, ful, let, map, out, soy, tai, ull

4 letters:
abor, agua, bali, ball, book, bose, dior, duse, elam, fact, fall, fula, goya, gray, irak, iran, iraq, life, lost, miri, name, over, peul, rare, reno, sand, tell, ullr, word

5 letters:
algol, alias, arius, benny, bizet, break, broca, brown, crohn, cymru, dafla, egypt, ellas, famed, flash, garbo, gismo, gizmo, hakka, harry, homer, intro, kesey, lassa, leary, lhasa, miami, moses, noted, novel, parvo, piece, pluto, raise, refer, roget, snead, sodom, tabun, tulsa, venus, wales, wells, wolfe

6 letters:
ankara, anselm, basque, before, biskek, bombie, cagney, callas, called, chabad, common, convey, cuvier, denote, doodad, emerge, eminem, entity, exilic, expose, famous, father, figure, foully, fowler, frunze, fulani, gibbon, graves, greece, gurkha, hadean, heller, hickey, highly, impart, judges, kinsey, let on, living, mirish, osmium, panini, parole, persia, powell, privyp, record, reiter, report, reveal, rhodes, secret, seward, spread, stuart, styron, sulfur, tabriz, temper, tucson, widely

7 letters:
adaxial, al-iraq, arcanum, archean, bandung, behrens, bishkek, cambria, clemens, daumier, diffuse, divulge, dominic, element, endless, gestapo, get out, gimmick, goodman, gubbins, insecta, let out, lithium, lobefin, logical, marconi, maurois, meniere, moderne, murdoch, newport, nineveh, notable, pickett, pretend, propose, ricinus, sargent, signify, simenon, soybean, spurner, strange, strauss, sulphur, susiana, sweeper, toponym, unknown, waikiki, wildcat

8 letters:
acapulco, anapsida, announce, archaean, bone age, cattleya, certainp, chlorine, columbia, come out, damascus, dateless, declared, definite, disclose, discover, disperse, dohickey, dojigger, explorer, familiar, famously, foreseen, foretold, hamilton, heedless, hexapoda, hoffmann, identity, ill fame, judgment, knowable, known as, landmark, liakoura, moluccas, nescient, neurosis, nevelson, nobelium, noumenon, password, priscoan, protease, renowned, reported, sauropod, schubert, schumann, skillful, sullivan, tefillin, unavowed, wernicke, whittier, winnipeg, ziegfeld

9 letters:
aborigine, agua toad, all along, amsterdam, anaphasic, anatolian, announced, anonymous, apophatic, bartholdi, blue chip, boyfriend, bring out, broadcast, buckyball, cancridae, caucasian, celebrity, chat show, circulate, date rape, deerhound, disclosed, doohickey, esoterica, far-famed, forgotten, free fall, galapagos, give away, go around, herodotus, highlands, innsbruck, isherwood, isoetales, ken kesey, lavoisier, lubavitch, man-eater, milwaukee, nashville, notoriety, obscurity, old world, otherness, palladian, parnassus, pasternak, peptidase, plutonium, predicted, propagate, protoavis, revealing, sam snead, stone age, surviving, talk show, thalassic, thingummy, tim leary, titration, transpire, watchword, wellerism, wodehouse, worm fish

10 letters:
aboveboard, adventurer, apophatism, bacitracin, balenciaga, best-known, blue whale, california, carnosaura, cataphatic, celebrated, cognisable, cognizable, consistent, dark horse, distribute, familiarly, fatherless, get around, giacometti, hadean eon, henceforth, hipparchus, identified, indefinite, index fund, jack benny, mark twain, motherless, new dealer, parvovirus, phenomenon, phylactery, place name, proclaimed, prominence, proteinase, proverbial, publicised, publicized, rubinstein, st. anselm, steel trap, technician, tenderloin, thingmabob, thingmajig, type genus, unfamiliar, unrevealed, well-known, well-mined, wildcatter

11 letters:
anacoluthic, angiomatous, cataphatism, circularise, circularize, coelophysis, cognoscible, combat zone, compromiser, cordaitales, countersign, disseminate, ed sullivan, emancipator, extrapolate, familiarity, george sand, giant squid, greta garbo, h. g. wells, hadean aeon, hadean time, illustrious, mesopotamia, metasequoia, miami beach, mustard gas, neuroticism, new zealand, open secret, pass around, record book, saturniidae, sempiternal, st. dominic, strangeness, thingamabob, thingamajig, thingumabob, thingumajig, thomas gray, unbelieving, undisclosed, well-knowna, white shark, wind tunnel

12 letters:
acknowledged, anaphylactic, architeuthis, basket maker, better-known, bufo marinus, cantharellus, cecil rhodes, chromic acid, clarence day, comprehended, coney island, dawn redwood, distinctness, emile herzog, flo ziegfeld, golden state, guide fossil, incognizable, index fossil, introduction, iris murdoch, james cagney, jimmy cagney, lucille ball, malacostraca, male bonding, maria callas, nitrous acid, presentation, priscoan eon, prosauropoda, quai d'orsay, robert brown, saint anselm, separateness, shostakovich, south africa, thomas wolfe, undetermined, vanadic acid, wildcat well

13 letters:
aegates isles, also known as, andre maurois, benny goodman, carbamic acid, carbonic acid, chlorous acid, church father, class insecta, deuteromycota, dutch capital, edward gibbon, eleonora duse, extrapolation, famous person, genus ricinus, georges bizet, hakka dialect, incognoscible, indeterminate, interpolation, joseph heller, karl wernicke, kiss of death, long-familiar, mustard agent, optical glass, passeriformes, peter behrens, priscoan aeon, psilophytales, public figure, robert graves, saint dominic, sarcosporidia, sound ranging, spice islands, sulfur bottom, timothy leary, triangulation, trouble-shoot, unfamiliarity, winslow homer

14 letters:
aegadean isles, alice hamilton, book of judges, christian dior, class hexapoda, columbia river, common wolffia, dichromic acid, disinclination, forbidden city, francisco goya, franz schubert, genus cattleya, georges cuvier, gilbert stuart, haplosporidian, helodermatidae, honore daumier, isocyanic acid, johann strauss, josef hoffmann, louis sullivan, psychoneurosis, siraj-ud-daula, sulfur mustard, william styron

15 letters:
ancient history, atomic number 3, blue-chip stock, boris pasternak, branta bernicla, cecil j. rhodes, crossopterygian, deuteromycotina, epsilon aurigae, georges simenon, internationally, ken elton kesey, louise nevelson, mount parnassus, order isoetales, p. g. wodehouse, prosper meniere, robert schumann, symbion pandora, thing-in-itself, turkish capital, venomous lizard, wheeled vehicle

16 letters:
artur rubinstein, atomic number 16, atomic number 17, atomic number 76, atomic number 94, bayes' postulate, blistering agent, capital of syria, capital of tibet, chabad-lubavitch, chemical element, common knowledge, face recognition, family cancridae, florenz ziegfeld, fungi imperfecti, goya y lucientes, imperial mammoth, lobe-finned fish, majority opinion, man-eating shark, mycelia sterilia, permanganic acid, peter mark roget, republic of iraq, struthioniformes

17 letters:
antoine lavoisier, arthur rubinstein, atomic number 102, baroness dudevant, benjamin kubelsky, black-legged tick, black huckleberry, capital of turkey, cecil john rhodes, deconstructionist, domingo de guzman, francisco de goya, galapagos islands, great white shark, gregory nazianzen, guglielmo marconi, habitual abortion, hellenic republic, histamine blocker, hypochlorous acid, imperial elephant, ixodes scapularis, order cordaitales, pierre-paul broca, satyendra n. bose, sauropod dinosaur, significant digit, subclass anapsida, the king of swing, upper-case letter, upper paleolithic

18 letters:
acapulco de juarez, agglutination test, alberto giacometti, anatolian language, caucasian language, cecil frank powell, common brant goose, facial recognition, family saturniidae, genus cantharellus, lubavitch movement, proteolytic enzyme, san joaquin valley, scottish deerhound, significant figure, triphosphoric acid, unification church, vanadium pentoxide, wolffia columbiana

19 letters:
dmitri shostakovich, gaylussacia baccata, henry watson fowler, john singer sargent, order passeriformes, order psilophytales, order sarcosporidia, robert ranke graves, satyendra nath bose, strauss the younger, suborder carnosaura

20 letters:
baron georges cuvier, buckminsterfullerene, capital of tennessee, cristobal balenciaga, father of the church, franz peter schubert, gregory of nazianzen, herbert george wells, louis henri sullivan, louis henry sullivan, samuel jackson snead, thomas clayton wolfe, united arab republic, william henry seward

21 letters:
alfred charles kinsey, balaenoptera musculus, burrill bernard crohn, capital of kyrgyzstan, christopher isherwood, dichloroethyl sulfide, family helodermatidae, genus corynebacterium, george edward pickett, highlands of scotland, palestinian hizballah, signature recognition, subclass malacostraca, suborder prosauropoda, timothy francis leary

22 letters:
arab republic of egypt, benjamin david goodman, carcharodon carcharias, dame jean iris murdoch, francisco jose de goya, gilbert charles stuart, maria meneghini callas, order mycelia sterilia, order struthioniformes, umar al-mukhtar forces

23 letters:
archidiskidon imperator, edward vincent sullivan, greta louisa gustafsson, john greenleaf whittier, negative identification, positive identification

24 letters:
accessory after the fact, circuit court of appeals, islamic republic of iran, major depressive episode, republic of south africa, samuel langhorne clemens, st. gregory of nazianzen

25 letters:
antoine laurent lavoisier, forces of umar al-mukhtar, hans conrad julius reiter, robert alexander schumann, subdivision deuteromycota

26 letters:
automatic face recognition, capital of the netherlands, frederic auguste bartholdi, pelham grenville wodehouse

27 letters:
amandine aurore lucie dupin, boris leonidovich pasternak, franz seraph peter schubert, subdivision deuteromycotina

28 letters:
metasequoia glyptostrodoides

31 letters:
dmitri dmitrievich shostakovich

32 letters:
georges joseph christian simenon

34 letters:
francisco jose de goya y lucientes

38 letters:
christopher william bradshaw isherwood

40 letters:
georges leopold chretien frederic dagobert cuvier