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Nadir
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<h2 id="etymology">Etymology</h2> <p>Although it entered English via other European languages, the word “nadir” is ultimately an <a href="/facts/Arabic/A1e66hVV">Arabic</a> <a href="/facts/Loanword/PWGYczgY">loanword</a>. It comes from the Arabic word “nazir”, meaning “opposite to”. More specifically, it originated from the Arabic phrase “nazir as-samt”, meaning “[the] opposite direction”.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p><p>Hebrew (whether <a href="/facts/Biblical_Hebrew/yCJ3bh30">ancient</a> or <a href="/facts/Modern_Hebrew/xIj94mYw">modern</a>) is a related language to Arabic, as they are both <a href="/facts/Semitic_languages/WCYrz4Qm">Semitic languages</a>.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> Hebrew also has a word “nadir” (נדיר), but with a somewhat different meaning: it is an adjective meaning “rare”.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> However, the same word also has a specialized usage to match its meaning in other languages like English.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> <h2 id="definitions">Definitions</h2> <h3>Space science</h3> <p>Since the concept of <i>being below</i> is itself somewhat vague, scientists define the nadir in more rigorous terms. Specifically, in <a href="/facts/Astronomy/0ArJVM1p">astronomy</a>, <a href="/facts/Geophysics/ywVQ1sAQ">geophysics</a> and related sciences (e.g., <a href="/facts/Meteorology/xblFr28q">meteorology</a>), the nadir at a given point is the local vertical direction pointing in the direction of the force of <a href="/facts/Gravitation/bqAN7DdQ">gravity</a> at that location. </p><p>The term can also be used to represent the lowest point that a <a href="/facts/Celestial_object/BCHLa0Q2">celestial object</a> reaches along its apparent daily path around a given point of observation (i.e. the object's <i>lower <a href="/facts/Culmination/qGHPjMRs">culmination</a></i>). This can be used to describe the <a href="/facts/Position_of_the_Sun/rNhWtukM">position of the Sun</a>, but it is only technically accurate for one <a href="/facts/Latitude/IBYqkjhU">latitude</a> at a time and only possible at the <a href="/facts/Tropics/Iv1es8Ih">low latitudes</a>. The Sun is said to be at the nadir at a location when it is at the zenith at the location's <a href="/facts/Antipodes/TqunGjML">antipode</a> and is 90° below the horizon. </p><p><i>Nadir</i> also refers to the downward-facing viewing geometry of an orbiting <a href="/facts/Satellite/PTX8c68t">satellite</a>,<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> such as is employed during <a href="/facts/Remote_sensing/pj2crmGs">remote sensing</a> of <a href="/facts/Atmosphere_of_Earth/FV97Am25">the atmosphere</a>, as well as when an <a href="/facts/Astronaut/HB1bd6Lz">astronaut</a> faces the Earth while performing a <a href="/facts/Spacewalk/udj91j1E">spacewalk</a>. A <i>nadir image</i> is a <a href="/facts/Satellite_image/V8LQh7jI">satellite image</a> or <a href="/facts/Aerial_photo/Sp9D0crM">aerial photo</a> of the Earth taken <a href="/facts/Vertical_direction/Hhsu9C8x">vertically</a>. A satellite <a href="/facts/Ground_track/HDgwB9RP">ground track</a> represents its orbit projected to nadir on to Earth's surface. </p> <h3>Medicine</h3><p> Generally in medicine, <i>nadir</i> is used to indicate the progression to the lowest point of a clinical symptom (e.g. fever patterns) or a laboratory count. In <a href="/facts/Oncology/t2CUAEJQ">oncology</a>, the term nadir is used to represent the lowest level of a blood cell count while a patient is undergoing <a href="/facts/Chemotherapy/fWTLbaUT">chemotherapy</a>.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> A diagnosis of <a href="/facts/Neutropenia/qasEurVu">neutropenic</a> nadir after chemotherapy typically lasts 7–10 days.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a></p> <h3>Figurative usage</h3> <p>The word is also used figuratively to mean a low point, such as with a person's <a href="/facts/Mood_(psychology)/mnozVozL">spirits</a>,<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> the quality of an activity or profession,<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> or the <a href="/facts/Nadir_of_American_race_relations/qKsQUgUf">nadir of American race relations</a>.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> </p> <h2 id="notes">Notes</h2> Look up <i>nadir</i> in Wiktionary, the free dictionary. <h2 id="references">References</h2> <ol> <li id="fn:1"><p>/ˈneɪdɪər, -dər/, also UK: /ˈnædɪər/; from Arabic: نظير [naðˤiːr], listenⓘ, ALA-LC: naẓīr, meaning "counterpart" <a href="/wiki/Help:IPA/English" target="_blank">/wiki/Help:IPA/English</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Although the English word Nadir comes from the Arabic naẓīr, the word "Nadir" in Arabic: (نادر) has a different meaning, which translates as 'rare' in English.[1] <a href="/wiki/Arabic_language" target="_blank">/wiki/Arabic_language</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>”nadir (n.)”. etymonline. Web. Accessed 18 Mar 2025. https://www.etymonline.com/word/nadir <a href="https://www.etymonline.com/word/nadir" target="_blank">https://www.etymonline.com/word/nadir</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Testen, David. “Semitic languages”. Encyclopedia Brittanica. Last updated 24 Feb 2025. Web. Accessed 18 Mar 2025. https://www.britannica.com/topic/Semitic-languages <a href="https://www.britannica.com/topic/Semitic-languages" target="_blank">https://www.britannica.com/topic/Semitic-languages</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>”Inflection of נדיר. Pealim [“Verbs”]. Web. Accessed 18 Mar 2025. https://www.pealim.com/dict/3316-nadir/ <a href="https://www.pealim.com/dict/3316-nadir/" target="_blank">https://www.pealim.com/dict/3316-nadir/</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>”nadir”. Do it in Hebrew. Hebrew-English online dictionary. Web. Accessed 18 Mar 2025. https://doitinhebrew.com/Translate/default.aspx?kb=US+US&l1=en&l2=iw <a href="https://doitinhebrew.com/Translate/default.aspx?kb=US+US&l1=en&l2=iw" target="_blank">https://doitinhebrew.com/Translate/default.aspx?kb=US+US&l1=en&l2=iw</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>McLaughlin, Richard J.; Warr, William H. (2001). "The Common Berthing Mechanism (CBM) for International Space Station" (PDF). Society of Automotive Engineers. Archived from the original (PDF) on September 15, 2006. Retrieved March 23, 2012. <a href="https://web.archive.org/web/20060915203048/http://spacecraft.ssl.umd.edu/design_lib/ICES01-2435.ISS_CBM.pdf" target="_blank">https://web.archive.org/web/20060915203048/http://spacecraft.ssl.umd.edu/design_lib/ICES01-2435.ISS_CBM.pdf</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"Bone marrow suppression". Chemotherapy Principles: An In-depth Discussion. American Cancer Society. Archived from the original on July 21, 2010. Retrieved March 5, 2013. <a href="https://web.archive.org/web/20100721225530/http://www.cancer.org/Treatment/TreatmentsandSideEffects/TreatmentTypes/Chemotherapy/ChemotherapyPrinciplesAnIn-depthDiscussionoftheTechniquesanditsRoleinTreatment/chemotherapy-principles-chemo-side-effects-bone-marrow-suppression" target="_blank">https://web.archive.org/web/20100721225530/http://www.cancer.org/Treatment/TreatmentsandSideEffects/TreatmentTypes/Chemotherapy/ChemotherapyPrinciplesAnIn-depthDiscussionoftheTechniquesanditsRoleinTreatment/chemotherapy-principles-chemo-side-effects-bone-marrow-suppression</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Le, Tao; Bhushan, Vikas; Skapik, Julia (2007). First Aid for the USMLE Step 2 CK (6. ed.). London: McGraw Hill Professional. p. 479. ISBN 978-0-07-159457-8. <a href="978-0-07-159457-8" target="_blank">978-0-07-159457-8</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Chisholm, Hugh, ed. (1911). "Nadir" . Encyclopædia Britannica. Vol. 19 (11th ed.). Cambridge University Press. p. 149. <a href="/wiki/Hugh_Chisholm" target="_blank">/wiki/Hugh_Chisholm</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Turner, Janice (December 1, 2007). "The lowest point in British journalism". The Times. Archived from the original on September 5, 2008. Retrieved March 23, 2012. <a href="https://web.archive.org/web/20080905234436/http://www.timesonline.co.uk/tol/comment/columnists/janice_turner/article2980262.ece" target="_blank">https://web.archive.org/web/20080905234436/http://www.timesonline.co.uk/tol/comment/columnists/janice_turner/article2980262.ece</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Logan, Rayford Whittingham (1997) [1965]. The betrayal of the Negro: from Rutherford B. Hayes to Woodrow Wilson (1. ed.). New York, NY: DaCapo Press. ISBN 978-0-306-80758-9. OCLC 35777358. <a href="978-0-306-80758-9" target="_blank">978-0-306-80758-9</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> </ol>