From Middle English curious, from Old French curius, from Latin cūriōsus.

• (RP) IPA: /ˈkjʊə.ɹi.əs/, /ˈkjɔː-/
• (America) IPA: /ˈkjʊ.ɹi.əs/, /ˈkjɚ.i.əs/, /-i.ɪs/
• (dialectal) IPA: /ˈkjʊ.ɹəs/

curious

1. Tending to ask questions, or to want to explore or investigate; inquisitive; (with a negative connotation) nosy, prying.

   Synonyms: enquiring, inquiring, exquisitive, investigative, peery

   Antonyms: incurious, noncurious, uncurious

   Young children are naturally curious about the world and everything in it.

   • 1816 June – 1817 April/May (date written), [Mary Shelley], chapter VII, in Frankenstein; or, The Modern Prometheus. […], volume III, London: […] [Macdonald and Son] for Lackington, Hughes, Harding, Mavor, & Jones, published 1 January 1818, →OCLC ↗, [https://babel.hathitrust.org/cgi/pt?id=emu.010001278703;view=1up;seq=197 page 189]:

     I shall quit your vessel on the ice raft which brought me thither and shall seek the most northern extremity of the globe; I shall collect my funeral pile, and consume to ashes this miserable frame, that its remains may afford no light to any curious and unhallowed wretch, who would create such another as I have been.

2. Caused by curiosity.
   • 1590, Edmund Spenser, “Book III, Canto IX”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie, →OCLC ↗, stanza 26, page 534 ↗:

     But he to ſhifte their curious requeſt, / Gan cauſen, why ſhe could not come in place; [...].

   • 1719 May 6 (Gregorian calendar), [Daniel Defoe], The Life and Strange Surprizing Adventures of Robinson Crusoe, […], London: […] W[illiam] Taylor […], →OCLC ↗, page 185 ↗:

     Such is the uneven State of human Life: And it afforded me a great many curious Speculations afterwards, when I had a little recovered my first surprise.

   • 1922 May 27, F[rancis] Scott Fitzgerald, “The Curious Case of Benjamin Button”, in Tales of the Jazz Age, New York, N.Y.: Charles Scribner's Sons, published September 1922, →OCLC ↗, part I, page 193 ↗:

     The doctor heard him, faced around, and stood waiting, a curious expression settling on his harsh, medicinal face as Mr. Button drew near.

3. Leading one to ask questions about; somewhat odd, out of the ordinary, or unusual.

   Synonyms: Thesaurus:strange

   Antonyms: uncurious

   The platypus is a curious creature, with fur like a mammal and a beak like a bird.

   • 1485 – Thomas Malory. Le Morte Darthur, Book X, Chapter xxxi, [https://quod.lib.umich.edu/c/cme/MaloryWks2/1:12.31?rgn=div2;view=fulltext leaf 232v]

     Thenne at the mete cam in Elyas the harper & by cause he was a curyous harper men herd hym synge the same lay that Dynadan had made

     "Then at the meat came in Eliot the harper, and because he was a curious harper men heard him sing the same lay that Dinadan had made"

   • 1719 May 6 (Gregorian calendar), [Daniel Defoe], The Life and Strange Surprizing Adventures of Robinson Crusoe, […], London: […] W[illiam] Taylor […], →OCLC ↗, page 34 ↗:

     I found him by his Blood ſtaining the water; and by the help of a Rope which I slung round him and gave the Negroes to hawl, they drag'd him on Shore, and found that it was a moſt curious Leopard, ſpotted and fine to an admirable Degree, and the Negroes held up their Hands with Admiration to think what it was I had kill'd him with.

   • 1865 November (indicated as 1866), Lewis Carroll [pseudonym; Charles Lutwidge Dodgson], “The Pool of Tears”, in Alice's Adventures in Wonderland, London: Macmillan and Co., →OCLC ↗, page 15 ↗:

     "Curiouser and curiouser!" cried Alice (she was so much surprised, that for the moment she quite forgot how to speak good English); "now I'm opening out like the largest telescope that ever was! Good-bye, feet!"

   • 1910, Emerson Hough, “A Lady in Company”, in The Purchase Price: Or The Cause of Compromise, Indianapolis, Ind.: The Bobbs-Merrill Company, →OCLC ↗, page 16 ↗:

     Captain Edward Carlisle, soldier as he was, martinet as he was, felt a curious sensation of helplessness seize upon him as he met her steady gaze, her alluring smile; he could not tell what this prisoner might do.

4. (LGBT) Clipping of bi-curious
5. (obsolete) Careful, fastidious, particular; (specifically) demanding a high standard of excellence, difficult to satisfy.
   • c. 1580 (date written), Philip Sidney, “(please specify the folio)”, in [Mary Sidney], editor, The Countesse of Pembrokes Arcadia […] [The New Arcadia], London: […] [John Windet] for William Ponsonbie, published 1593, →OCLC ↗:

     Honourable even in the curiousest pointes of honour, whereout there can no disgrace nor disperagement come unto her.

   • c. 1610–1611 (date written), William Shakespeare, “The Winters Tale”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC ↗, [Act IV, scene iv], page 295 ↗, column 2:

     I am ſo fraught with curious buſineſſe, that / I leaue out ceremony.

   • 1624, Richard Pots, William Tankard, G. P., William Simons, compiler, “Chap. VIII. Captaine Smiths Iourney to Pamavnkee.”, in Iohn Smith, The Generall Historie of Virginia, New-England, and the Summer Isles: […], London: […] I[ohn] D[awson] and I[ohn] H[aviland] for Michael Sparkes, →OCLC ↗, book 3; reprinted in The Generall Historie of Virginia, [...] (Bibliotheca Americana), Cleveland, Oh.: The World Publishing Company, 1966, →OCLC ↗, page 74 ↗:

     [We] never had better fires in England, then in the dry, ſmoaky houſes of Kecoughtan: but departing thence, when we found no houſes we were not curious in any weather to lye three or foure nights together vnder the trees by a fire, [...]

6. (obsolete) Carefully or artfully constructed; made with great elegance or skill.
   • 1576, George Whetstone, “The Castle of Delight: […]”, in The Rocke of Regard, […], London: […] [H. Middleton] for Robert Waley, →OCLC ↗; republished in J[ohn] P[ayne] Collier, editor, The Rocke of Regard, […] (Illustrations of Early English Poetry; vol. 2, no. 2), London: Privately printed, [1867?], →OCLC ↗, page 44 ↗:

     To honour which a worlde of people reſorted unto the Lord de Bolognas caſtle; for the intertainment of whiche gueſtes, there neither wanted coſtly cheare, curious ſhewes, or pleaſaunt deviſes, that eyther money, friendſhip or cunning might compaſſe.

   • c. 1591–1592 (date written), William Shakespeare, “The Third Part of Henry the Sixt, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC ↗, [Act II, scene v], page 156 ↗, column 2:

     His wonted ſleepe, vnder a freſh trees ſhade, / All which ſecure, and ſweetly he enjoyes, / Is farre beyond a Princes Delicates: / His Viands ſparkling in a Golden Cup, / His bodie couched in a curious bed, / When Care, Miſtrust, and Treaſon waits on him.

   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC ↗, Exodus 28:8 ↗:

     And the curious girdle of the Ephod, which is upon it, ſhall bee of the ſame, according to the worke thereof; euen of gold, of blew, and purple, and ſcarlet, and fine twined linnen.

   • 1665, R[obert] Hooke, “Observ[ation] I. Of the Point of a Sharp Small Needle.”, in Micrographia: Or Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses. […], London: […] Jo[hn] Martyn, and Ja[mes] Allestry, printers to the Royal Society, […], →OCLC ↗, pages 1–2 ↗:

     [I]f view'd with a very good Microſcope, we may find that the top of a Needle (though as to the ſenſe very ſharp) appears a broad, blunt, and very irregular end; not reſembling a Cone, as is imagin'd, but onely a piece of a tapering body, with a great part of the top remov'd, or deficient. The Points of Pins are yet more blunt, and the Points of the moſt curious Mathematital Inſtruments do very ſeldome arrive at ſo great a ſharpneſs; [...]

• curiosity
• curiosity killed the cat
• curio
• incurious
• incuriously
• incuriousness

• French: curieux
• German: neugierig
• Italian: curioso, interessato
• Portuguese: curioso
• Russian: любопы́тный
• Spanish: curioso

• French: curieux
• German: kurios
• Italian: curioso, strano
• Portuguese: curioso, estranho
• Russian: курьёзный
• Spanish: curioso, extraño, raro

From curium + -ous.

curious (not comparable)

1. (inorganic chemistry, rare) Containing or pertaining to trivalent curium.