The three-syllable word HIDEOUS, with the change of a single consonant, becomes a two-syllable word with no vowel sounds in common: HIDEOUT [Mark D. Lew].
HIV VIRUS is an obvious redundancy, since the "v" stands for "virus." Some other common redundancies which include an abbreviation are ATM MACHINE, SALT TALKS, START TALKS, VIN NUMBER, PIN NUMBER, AC CURRENT, DC CURRENT, ISBN NUMBER, DOS OPERATING SYSTEM, ABS BRAKING SYSTEM, DIMM MODULE (Dynamic Inline Memory Module), EFT TRANSFER (Electronic Funds Transfer), EMP PULSE (Electromagnetic Pulse), and MSDS SHEETS (Material Safety Data Sheet), DC COMICS (DC = Detective Comics) [Thomas Larson, Nate Roe, Charles Turner, Ana Perez, and others]. THE EL CAMINO HIGHWAY in California translates to “The the highway highway” [Bill Farrell]. Since iterate means “to repeat,” REITERATE could be considered a redundancy [Bill Farrell].
LCD DISPLAY (Liquid Crystal Display) has been suggested for this category, but Mark Brader says it is not a redundancy. He writes, "The first 'display' refers to an individual character (or similar component), the second to the whole array of these. The big display is made up of little displays."
[The Cyber Stylebook of the San Antonio Express-News states that RIO GRANDE RIVER is a redundancy since Rio means "river." There are numerous similar place names such as Gobi and Sahara deserts, Fujiyama and Sierra mountains, La Brea Tar Pits, etc.; however, these are generally not considered redundancies because they involve two languages.]
HONORIFICABILITUDINITATIBUS is the longest word consisting entirely of alternating vowels and consonants. (For information on this word, see the long words section.) Other such words are ALUMINOSILICATES, CYTOMEGALOVIRUSES, DEPOLARIZABILITY, EPICORACOHUMERALER, HETEROZYGOSITY, HEXOSAMINIDASES, HYPOVITAMINOSISES, ICULANIBOKOLAS (plural of a cannibal fork mentioned in the March 2003 National Geographic), PARAMYXOVIRUSES, PARAROSANILINES, PARASITOLOGICAL, SUPEREROGATORILY, TENOSYNOVITIDES, TENOSYNOVITISES, UNIMAGINATIVELY, VERISIMILITUDES [Stuart Kidd, Paul F. Doering, Charles Turner]. An endangered Hawaiian plant, Abutilon eremitopetalum, and a recently extinct burrowing mammal from Madagascar, Malagasy bibymalagasy, alternate vowels and consonants [Charles Turner, Mark Isaak, "Curiosities of Biological Nomenclature"]. LATERAL ALA NASI, defined as "a soft tissue landmark formed by the lateral attachment of the ala nasi (the outer flaring wall of each nostril) with the cheek," appears in Principles and Practices of Radiation Therapy [Charles Turner].
IMMUNOHEMATOLOGIC contains 8 pairs of alternating vowels and consonants.
Some words containing 7 pairs of alternating vowels and consonants are: ALUMINOSILICATE, AUTOMANIPULATIVE, DELIBERATIVENESS, GELATINIZABILITY, HYPEROXYGENIZES, IMAGINATIVENESS, INERADICABILITY, INOPERATIVENESS, MEGALOPOLITANISM, PHENOMENOLOGICAL, PHOTOPOLYMERIZATION, PRECIPITINOGENIC, PREFIGURATIVENESS, REMUNERATIVENESS, SEMIMINERALIZED, UNAPOLOGETICALLY, UNILATERALIZATION, UNILATERALIZES, VERISIMILITUDINOUS [Nelson H. F. Beebe].
Craig Kasper says GORAN IVANESEVIC (a top tennis player) may be the longest name of a relatively famous person that alternates consonants and vowels.
UNITED ARAB EMIRATES is the longest name of a country consisting of alternating vowels and consonants.
Other place names consisting of alternating vowels and consonants include GULEMALAMALALANA Point in Papua New Guinea, REBUREBUSIWASIWA (a Papuan town), KAWAKAWAMALAMALA (a Fijian stream), PROMYSEL IMENI NARIMANOVA (a village in Azerbaijian) [Juozas Rimas], and WEROWOCOMOCO (Indian place name on John Smith's map of Virginia) [Charles Turner].
Juozas Rimas reports that Fijian streams NAIVUTUVUTUNIVAKALOLO and NONDRAISILISILINAYALEWATONGA have even longer sequences of alternating vowels and consonants (19 and 20) but the sequences constitute only part of the words.
Some Japanese place names with alternating vowels and consonants include: KAKINOKIZAKA (district in Meguro, Tokyo), KASUMIGASEKI (district in Chiyoda, Tokyo), and TAKADANOBABA (district in Shinjuku, Tokyo). These spellings use the widely-recognized Hepburn system for the Romanized alphabet version of Japanese words. In this system, all Japanese ideographic and phonetic characters can be represented by a "vowel-only" or "consonant(sound)-vowel" combination [Joseph Hernandez].
The earliest known appearance of the word HELLO in print is in a letter written by Thomas Edison dated August 15, 1877. In the letter, addressed to T. B. A. David, president of Central District and Printing Telegraph Company in Pittsburgh, Edison suggested that the word should be used to answer the telephone. HELLO is an alteration of the much older word HOLLO.
HYPoThAlAmICoHYPoPHYSeAlS is the longest word that can be spelled using chemical symbols. Other such words include NONRePReSeNTaTiONAlISmS, BrONCHOEsOPHAgOSCOPIEs, ThErMoPHOSPHOReSCeNCe, HYPSIBRaCHYCePHAlISm, HYPErPHOSPHOReSCeNCe, SUPErCoNdUCTiVITiEs, PARaPrOFeSSiONaLS, and SUPErSOPHISTiCAtE [Stuart Kidd]. IrReSPONSiBILiTiEs reuses no element’s symbol [Mike Keith]. PrAcTiCaLiTiEs may be the longest word using only two-letter abbreviations, or PaRaCrOsTiCs if no elements are repeated [Richard Sabey].
HYDROXYZINE (a prescription drug) is the only word in RHUD2, OED2, and W3 containing XYZ. Allowing scientific names in biology, there is XYZZORS (a nematode worm) [Stuart Kidd]. XYZAL is a newer prescription drug [Dennis Miller].
The most commonly used words in spoken English are I, YOU, THE, and A.
The most commonly used words in written English, according to the 1971 American Heritage Word Frequency Book are: the, of, and, a, to, in, is, you, that, it, he, for, was, on, are, as, with, his, they at, be, this, from, I, have, or, by, one, had, not, but, what, all, were, when, we there, can, an, your, which, their, said, if, do.
The most commonly occurring words in Shakespeare's plays and poetry (with frequencies) are: the 29854, and 27554, I 23357, to 21075, of 18520, a 15523, you 14264, my 12964, that 11955, in 11842, is 9734, not 8871, with 8269, s 8160, for 8100, it 8080, me 8059, 7357 his, 7228 be, 7120 he. In Shakespeare, 8598 words (abaissiez, abash, abatements, abates, abbeys, ..., zo, zodiac, zodiacs, zone, zwaggered) are used only once [Nelson H. F. Beebe].
The most commonly occurring sound in spoken English is the sound of a in alone, followed by e as in key, t as in top, and d as in dip [Stuart Kidd].
The longest word with a horizontal line of symmetry is COCCIDIOCIDE [Paul Wright]. Some other words are: BEDECKED, BOOHOOED, CEBID (a type of monkey), CHECKBOOK, CHOICE, CODEBOOK, COOKBOOK, DECIDED, DIOXIDE, DOBCHICK, EXCEEDED, HIDE, HOODOOED, ICEBOX, KEBOBBED, OBOE, OKEECHOBEE, and OXOBOXO (a small lake in southeastern Connecticut, also a palindrome). [Dmitri Borgmann, Stuart Kidd]
Some words with a vertical line of symmetry are MOM, WOW, OTTO, MAAM, MA'AM, TOOT, AHA, AA, AHA, AIA, AMA, AVA, AWA, HAH, HOH, HUH, MAM, MIM, MM, MUM, OHO, OO, OXO, TAT, TIT, TOT, TUT, UTU, VAV, WAW.
All of the letters of these words have a vertical line of symmetry: AUTOMATA, AUTOTOMY, HIMATIA, HOITY-TOITY, HOMOTAXIA, MAHATMA, MAHIMAHI, MAMMATI, MAMMOTH, MATAMATA, MOTIVITY, MOUTH-TO-MOUTH, MYOMATA, MYXOMATA, OUTWAIT, TATOUAY, TAXIWAY, THATAWAY, TIMOTHY, TOMATO, TOWAWAY, WITHOUT, YAWATAHAMA (a city in Japan), and YOUTH.
Upper case BID is horizontally reflective while lower case bid is vertically reflective [Hugo Brandt Corstius].
SWIMS has 180-degree rotational symmetry. If written in lower-case cursive, chump comes very close to having 180-degree rotational symmetry [Mark D. Lew].
These words with 6 or more letters have all letters rotationally symmetrical: NINONS, ONIONS, SISSOOS, SOZINS, ZOONOSIS, ZOOZOOS.
All of the letters of these words have both horizontal and vertical lines of symmetry: HI, OH, IO, OHIO, OHO, and IHI'IHI (rare Hawaiian fern that now exists only in three populations, two of which are inside volcanoes) [Bruce D. Wilner, Dan Tilque, Mike Turniansky].
IFF is a word used in mathematics to mean "if and only if." According to MWCD11, it can be pronounced three ways: "if and only if," like "if," and like "if" but with a prolonged "F." There are 121 conjunctions in MWCD11; IFF is the only conjunction that is a new word, as it was first seen in print in 1955. Other new conjunctions in MWCD11 are NEVER MIND (1954), PLUS (1950), and UNLIKE (1949). The newest prepositions are OFFSHORE (1965), ANTI (1953), and APRÉS (1951) [Dan Tilque].
The following words have 75% of their letters the same: IIWI (a Hawaiian bird), BIBB, FAFF, LALL, LILL, LOLL, LULL, MUMM, SASS, SESS, SISS, SOSS, SUSS ("Suss out" is British slang for "figure out"), SYSS, TATT, ZIZZ, ÉPÉE (a fencing sword), DODD, EEFE, EESE, EETE, ESEE, FEFF, FIFF, FUFF, GEGG, GUGG, LELL, and NONN [Byron Davidson, Daniel Steinberg, Philip Bennett].
IMPETICOS is an example of a nonce word (a word which has been found to have been used only once). The word is spoken by the clown in Shakespeare's Twelfth Night. W2 says perhaps it means "impocket."
INTERCHANGEABILITY contains the letters of the words THREE, EIGHT, NINE, TEN, THIRTEEN, THIRTY, THIRTY-NINE, EIGHTY, EIGHTY-NINE, NINETY, and NINETY-EIGHT [Stuart Kidd].
INTESTINES has each of its letters occurring twice. Some other such words: APPEASES, ARRAIGNING, BERIBERI, BILABIAL, CAUCASUS, CHOWCHOW, CICADELLIDAE, CONCISIONS, COUSCOUS, ESOPHAGOGRAPHERS, FROUFROU, GENSENGS, GREEGREE, GUITGUIT, HAPPENCHANCE, HORSESHOER, HOTSHOTS, INACCIDENTATED, JIPIJAPA, MAHIMAHI, MESOSOME, MILLIEME, MIMETITE, RAPPAREE, REAPPEAR, SCINTILLESCENT, SHAMMASH, SHANGHAIINGS, SIGNINGS, TAENIODONTIDAE, TEAMMATE, UNSUFFICIENCES, VETITIVE [Pierre Abbat, Stuart Kidd, Philip C. Bennett, Charles Turner].
The shortest word with six letters appearing at least twice is METASOMATOSES [Stuart Kidd].
IO (an interjection in Chambers and one of the moons of Jupiter), AI (the three-toed sloth), EO, OK, and AA (rough volcanic rock) seem to be the shortest two-syllable words.
IRAQ is one of the very few words ending in Q. Obscure words ending in Q are: ABQAIQ (a city in Saudi Arabia), AUYUITTUQ (National Park in Canada), CINQ (an alternative spelling of "cinque," OED), FARUQ (former king of Egypt, also spelled "Farouk"), HALQ AL-WADI (city in Tunisia), INUPIAQ (an Eskimo people), IQ, KANGIQSUALUJJUAQ (an Inuit village in Quebec), KUUJJUAQ (a Canadian village), N'ASTALIQ, NESTALIQ (alternative spelling of "nastalik," OED), PDQ, PONTACQ, QAANAAQ (settlement in Greenland; it's also a palindrome), QAZAQ (alternative spelling of "Kazakh," OED), QEQERTARSUAQ (island in Greenland), QUTTINIRPAAQ (National Park in Canada) RENCQ (obsolete spelling of "rank," OED), SADIQ (a city in India), SAMBUQ (alternative spelling of "sambuk," OED) SHOQ, SUQ, ZAQAZIQ (or ZAGAZIG, a city in Egypt), TALAQ (in Chambers), TRANQ (in OSPD), TZADDIQ (in Chambers; can also be spelled TSADDIQ), UMIAQ (a variant spellling of UMIAK, an Eskimo boat, in W2 and W3), ZIA-UL-HAQ (a proper name) [Dave Baker, Phillip Bennett, Eric Brahinsky].
KÄRNTEN (one of the states of Austria) has 8 pairs of alternating dits and dahs in Morse code (-.- .-.- .-. -. - . -.) [Pierre Abbat]. A Finnish word for "focusing" has a 9 pairs of 18 alternating dits and dahs: TARKENTAEN (- .- .-. -.- . -. - .- . -.) [Pertti Malo].
A Finnish tongue twister for "a water devil hissed in the elevator" has 56 dits in a row in Morse code. It has a total of 60 dits and 3 dahs which is the greatest ratio (20:1) known in any mix. VESIHIISI SIHISI HISSISSÄ (...- . ... .. .... .. .. ... .. ... .. .... .. ... .. .... .. ... ... .. ... ... .-.-) [Pertti Malo, Mark Brader].
MOTMOT (a tropical American bird) and TOM-TOM (ignoring the hyphen) contain only dahs in Morse code (-- --- - -- --- -) and (- --- -- - --- --) [Chris Cole, Byron Davidson].
SHEESHES (plural of SHEESH) may be the longest word containing only dits in Morse code (... .... . . ... .... . ...) [Byron Davidson].
In English, ignoring spaces, the longest palindrome in Morse code is INTRANSIGENCE (.. -. - .-. .- -. ... .. --. . -. -.-. .) [Chris Cole]. If spaces are not ignored, the longest word is FOOTSTOOL (..-. --- --- - ... - --- --- .-..) [Andrew Dart]. The Finnish word for "stereo mapping" is even longer with 33 characters: STEREOKARTOITUS (... - . .-. . --- -.- .- .-. - --- .. - ..- ...) [Pertti Malo].