ID Endings: Science, Scrabble, and Six-Letter Crossword Answers
BID, DID, HID, KID, LID, RID — the three-letter ID words are some of the first words children learn to read. But the ID ending really gets interesting at five letters and beyond, where scientific terminology takes over. ARACHNID, ASTEROID, THYROID, ANDROID, PYRAMID — these words use -ID and -OID suffixes borrowed from Greek, meaning "resembling" or "having the form of." HUMANOID means resembling a human, ASTEROID resembles a star (at least that's what the Greeks thought). This Greek -OID pattern is one of the most productive in scientific English and shows up in crossword puzzles constantly.
For Scrabble players, the ID ending is tactically valuable. The I and D tiles are both common in racks (I appears 9 times in a standard set, D appears 4 times), so you'll often have the raw materials. ACRID (8 points), FETID (9 points), and LUCID (8 points) are five-letter words that score modestly but play well on tight boards. The standout move is SQUID — it's 15 points base and uses the Q-U combination that most players struggle to deploy. Competitive players also memorize -ID words that double as adjective hooks: RAPID, VIVID, SOLID, STUPID can all take -LY to extend on the board.
Explore related patterns at words starting with C for dozens of scientific -ID terms, words starting with UN for UNDID and other negated forms, and words starting with P for PYRAMID, PLACID, and more. Also try words starting with D for words where D appears at both ends.
FAQ
What does the -OID suffix actually mean?
From Greek -oeides, meaning "resembling" or "having the form of." ASTEROID means star-like, ANDROID means human-like, THYROID means shield-shaped. It's one of the most consistent Greek suffixes in English. For more Greek-rooted vocabulary, browse words starting with E and words starting with P.
What three-letter ID words are valid in Scrabble?
AID, BID, DID, GID, HID, KID, LID, MID, RID are all valid. GID (a disease in sheep caused by a brain parasite) is the one most players don't know. These short words are perfect for parallel plays. Check words starting with F for FID and related openings, or words starting with X for less common tile combinations.
Three-Letter Words (12)
AIDBIDDIDFIDGIDHIDKIDLIDMIDRIDVIDYID
Four-Letter Words (23)
ACIDAMIDARIDAVIDCAIDCHIDGRIDGUIDIMIDIRIDLAIDLOIDMAIDOXIDPAIDQAIDQUIDRAIDSAIDSKIDSLIDVOIDWHID
Five-Letter Words (66)
ACRIDALCIDALGIDAPHIDAROIDAVOIDBIFIDBOVIDBRAIDCANIDCEBIDCUPIDDROIDDRUIDEQUIDFELIDFETIDFLUIDGADIDGELIDGEOIDHALIDHUMIDHYOIDIODIDJERIDLIPIDLIVIDLUCIDLURIDMUCIDMURIDMYOIDMYSIDNITIDOOTIDOVOIDPAVIDPLAIDPYOIDRABIDRANIDRAPIDREBIDREDIDRESIDRIGIDSAPIDSAYIDSLOIDSOLIDSQUIDSTAIDTABIDTEIIDTEPIDTIMIDTUMIDUNBIDUNDIDURSIDVALIDVAPIDVIRIDVIVIDZOOID
Six-Letter Words (109)
ACARIDAFRAIDAGAMIDALGOIDARAMIDBEDRIDBROMIDCANDIDCAPSIDCEBOIDCERVIDCLERIDCOCCIDCONOIDCORVIDCOSMIDCUBOIDCUSPIDCYANIDCYMOIDDESMIDDEVOIDDIACIDDIOXIDELAPIDEYELIDFERVIDFLORIDFOETIDFORBIDFORDIDFRIGIDFUCOIDFULGIDGADOIDGANOIDGRAVIDHALOIDHEMOIDHISPIDHORRIDHYBRIDHYDRIDINLAIDIXODIDJASSIDJERRIDKELOIDKIDVIDLIMPIDLIPOIDLIQUIDMANTIDMASJIDMELOIDMISDIDMORBIDMUCOIDMUSCIDMUSJIDMYXOIDNAVAIDNEREIDNEVOIDNITRIDOPIOIDORCHIDOUTBIDOUTDIDOZALIDPALLIDPEPTIDPLACIDPONGIDPREBIDPSOCIDPUTRIDRANCIDRELAIDREPAIDRESAIDSAIYIDSALPIDSAYYIDSIALIDSORDIDSPARIDSTOLIDSTUPIDSULFIDTINEIDTOLUIDTOROIDTORPIDTORRIDTOXOIDTREPIDTRIFIDTURBIDTURGID
and 9 more — use the solver above to search
Seven-Letter Words (164)
ACAROIDADENOIDAGATOIDAMBROIDAMEBOIDAMYLOIDANDROIDANEROIDANNELIDANTACIDANTHOIDARANEIDASCARIDBANDAIDBARMAIDBESTRIDCACTOIDCAMELIDCARABIDCAROTIDCEPHEIDCESTOIDCHALCIDCHELOIDCHLORIDCHOROIDCHYTRIDCICHLIDCIRSOIDCISSOIDCLUPEIDCOCCOIDCOLLOIDCORMOIDCRICOIDCRINOIDCTENOIDCULICIDCYCLOIDCYSTOIDDELTOIDDENTOIDDERMOIDDESMOIDDIAPSIDDIPLOIDDISCOIDEMEROIDENERGIDERICOIDETHMOIDEUPLOIDFACTOIDFIBROIDFLACCIDFLUORIDFOREDIDFUNGOIDGLENOIDGLOBOIDGLOCHIDGOBIOIDHAEMOIDHAPLOIDHISTOIDHOMINIDHYALOIDHYDATIDHYDROIDHYENOIDHYPNOIDIGUANIDIMPAVIDINSIPIDINVALIDKATYDIDLABROIDLANGUIDLENTOIDLEPORIDLIANOIDLITHOIDMASTOIDMATTOIDMERMAIDMISLAIDMISSAIDMONACIDMYELOIDNAEVOIDNAYSAIDNEGROIDNEUROIDNOCTUIDNONACIDNONPAIDNONSKIDOBOVOIDOCELOIDOCHROID
and 64 more — use the solver above to search
Eight-Letter Words (176)
ACETAMIDACTINOIDALKALOIDAMBEROIDAMMONOIDAMOEBOIDANCONOIDANTHERIDANTISKIDARACHNIDARILLOIDASTEROIDATHETOIDAUTACOIDAUTOCOIDBACKSLIDBICUSPIDBIOSOLIDBOMBYCIDBONDMAIDBOTRYOIDBRACONIDCANCROIDCARANGIDCARDIOIDCARYATIDCATENOIDCENTROIDCERATOIDCHARACIDCHARQUIDCHOREOIDCHORIOIDCLUPEOIDCOLUBRIDCOMORBIDCONCHOIDCORACOIDCORONOIDCOTYLOIDCOVERLIDCRICETIDCYANAMIDCYPRINIDDENDROIDDIHYBRIDDISULFIDECHINOIDELATERIDELYTROIDEMBRYOIDEMULSOIDEUGLENIDEUPATRIDFILARIIDFORESAIDGABBROIDGAINSAIDGRANDKIDGROUPOIDGYNECOIDHANDMAIDHELICOIDHEMATOIDHOMINOIDHUMANOIDHYDRACIDHYPOACIDHYRACOIDILLIQUIDINDIGOIDINTREPIDINVISCIDISTHMOIDKERATOIDLACERTIDLAMBDOIDLAMPYRIDLANDSLIDLEMUROIDLIGULOIDLIMULOIDLYMPHOIDMANATOIDMEDICAIDMEDUSOIDMELANOIDMILKMAIDMONOACIDMUCINOIDMULTIFIDMURAENIDMUSTELIDMYCELOIDNOCTUOIDNONFLUIDNONRIGIDNONSOLIDNONVALIDNUCLEOID
and 76 more — use the solver above to search
Nine-Letter Words (120)
ACANTHOIDAFORESAIDALLANTOIDANEUPLOIDAPARTHEIDARACHNOIDARYTENOIDBACTEROIDBENZENOIDBIPYRAMIDBLENNIOIDBOMBYCOIDBUPRESTIDCARANGOIDCARCINOIDCELLULOIDCHANCROIDCHITINOIDCHOLEROIDCHROMATIDCHRYSALIDCOMATULIDCONDYLOIDCORALLOIDCORNBRAIDCORTICOIDCRETINOIDCYCADEOIDCYPRINOIDDAIRYMAIDDEMANTOIDDERMATOIDDERMESTIDECHIUROIDELLIPSOIDEPHEMERIDERIOPHYIDERYTHROIDEUGLENOIDEUNUCHOIDEUPHAUSIDEUTECTOIDEUTHYROIDFALCONOIDFIBRINOIDFLAVONOIDFUSULINIDGAVIALOIDGEOMETRIDGNEISSOIDGRANITOIDHEXAPLOIDHOUSEMAIDHYPERACIDHYPERARIDHYPOPLOIDHYSTEROIDICHTHYOIDINTERLAIDISONIAZIDLABELLOIDLEUKEMOIDMARASMOIDMENISCOIDMETALLOIDMETEOROIDMONGOLOIDMONOPLOIDMONORCHIDMULTIGRIDNAUTILOIDNONLIQUIDNURSEMAIDNYMPHALIDOCTOPLOIDOPHIUROIDORNITHOIDOVERPLAIDOVERRIGIDOVERTIMIDOVERVIVIDPERFERVIDPITHECOIDPLANETOIDPLANULOIDPLATINOIDPOLYPLOIDPTERYGOIDPYRALIDIDQUADRIFIDQUINONOIDSALMONOIDSANGFROIDSATURNIIDSCARABOIDSCHOOLKIDSCIAENOIDSCIRRHOIDSCOMBROIDSCORPIOID
and 20 more — use the solver above to search
Ten-Letter Words (43)
ACETANILIDAMPHIPLOIDAMYGDALOIDANTHROPOIDBRIDESMAIDCAROTENOIDCAROTINOIDCHIRONOMIDCOUNTERBIDDISPERSOIDEICOSANOIDEPICYCLOIDEPIDERMOIDEPILEPTOIDEUPHAUSIIDEURYPTERIDGLYCOLIPIDHEMORRHOIDHYPERPLOIDIPRONIAZIDISOPRENOIDMONOHYBRIDNONSTEROIDPARABOLOIDPARASITOIDPENTAPLOIDPINNATIFIDPREHOMINIDPRISMATOIDPROBENECIDPROCERCOIDPROGLOTTIDPROPLASTIDPYCNOGONIDPYRETHROIDPYROXENOIDRHEUMATOIDSCORPAENIDSEMILIQUIDSPHENOPSIDSUPERFLUIDTETRAPLOIDULTRARAPID
Eleven-Letter Words (21)
ANTITHYROIDANTITYPHOIDCANNABINOIDCHAMBERMAIDCHRYSOMELIDCOUNTERRAIDCRYPTORCHIDCRYSTALLOIDDIPHTHEROIDEPITHELIOIDHETEROPLOIDHYPERBOLOIDHYPOCYCLOIDHYPODIPLOIDHYPOTHYROIDKETOSTEROIDPARATHYROIDPARATYPHOIDSTAPHYLINIDTENEBRIONIDTUBERCULOID
Twelve-Letter Words (10)
AMPHIDIPLOIDCYSTICERCOIDHYDROCOLLOIDHYPERTHYROIDNUCLEOCAPSIDORTHOPTEROIDPHOSPHOLIPIDPLEROCERCOIDSPERMATOZOIDSUBARACHNOID
Thirteen-Letter Words (7)
ALLOPOLYPLOIDANAPHYLACTOIDANTIAPARTHEIDAUTOPOLYPLOIDENDOPOLYPLOIDHYPOEUTECTOIDISOCARBOXAZID
Fourteen-Letter Words (7)
ALLOTETRAPLOIDAUTOTETRAPLOIDCORTICOSTEROIDGLUCOCORTICOIDHYPEREUTECTOIDMICROMETEOROIDPHILANTHROPOID