Kahlbaum;Kahlbaum, Georg Wilhelm August: 1853 to 1905, chemist
Kamerlingh-Onnes;Kamerlingh-Onnes, Heike: 1853 to 1926, physicist and chemist
Kapiza;Kapitza, Pyotr Leonidovich: 1894 to 1984, physicist
Kaplan;Kaplan, Viktor: 1876 to 1934, engineer
Karmarsch;Karmarsch, Karl: 1803 to 1879, engineer
Karolus;Karolus, August: 1893 to 1972, physicist
Kater;Kater, Henry: 1777 to 1835, engineer
Kay;Kay, John: 1704 to 1764 (1774), engineer
Keller;Keller, Friedrich Gottlob: 1816 to 1895, engineer
Kelvin;Unit of temperature named after British physicist Lord Kelvin.
Kelvin Lord;Lord Kelvin of Largs (formerly William Thomson): 1824 to 1907, physicist
Kepler;Kepler, Johannes (1571-1630), German astronomer, astrologist, mathematician and philosopher
Kerr;Kerr, John: 1824 to 1907, physicist
Kettering;Kettering, Charles Franklin: 1876 to 1958, engineer
Kibalchich;Kibalchich, Nikolai Ivanovich: 1854 to 1881, engineer
Kilby;Kilby, Jack S.: (* 1923), physicist and inventor
Kircher;Kircher, Athanasius: 1601 to 1680, scholar
Kirchoff;Kirchoff, Gustav Robert: 1824 to 1887, physicist
Kjellin;Kjellin, Frederic Adolf: 1872 to 1910, engineer
Klaproth;Klaproth, Martin Heinrich: 1743 to 1817, chemist and pharmacist
Kleist;Kleist, Georg Ewald von: 1700 to 1748, naturalist
Knietsch;Knietsch, Rudolf Joseph Theophil: 1854 to 1906, chemist
Knoll;Knoll, Max (1897-1969), German electrical engineer
Knorr;Knorr, Georg: 1859 to 1911, engineer
Knots;A knot is a unit of speed used to measure the movement of a ship or aircraft. A knot or "kn" is a nautical mile per hour. It equals 1.852km per hour. 
Koehnen;Koehnen, Matthias: 1849 to 1924, civil engineer
Koenig;Koenig, Friedrich: 1774 to 1833, engineer
Kohlrausch;Kohlrausch, Friedrich Wilhelm Georg: 1840 to 1910, physicist
Kolbe;Kolbe, Hermann: 1818 to 1884, chemist
Korn;Korn, Arthur: 1870 to 1945, physicist
Korolyov;Korolyov, Sergei Pavlovich: 1906 to 1966, rocket and space travel pioneer
Kossel;Kossel, Walther: 188 to 1956, physicist
Kotelnikov;Kotelnikov, Vladimir Aleksandrovich: (* 1908), radio frequency engineer
Krarup;Krarup, Karl Emil: 1872 to 1909, engineer
Kress;Kress, Willhelm: 1836 to 1913, Aviation pioneer
Kreutzberger;Kreutzberger, Freidrich Wilhelm: 1822 to 1918, engineer
Krylov;Krylov, Alexei Nikolayewich: 1863 to 1945, physicist
Kulibin;Kulibin, Ivan Petrovich: 1735 to 1818, engineer
Kunkel;Kunkel von Löwenstern, Johann: 1638 to 1703, alchemist and glassmaker
Kurchatov;Kurchatov, Igor Vasilyevich: 1903 to 1960, physicist
Kwolek;Kwolek, Stephanie Louise: (* 1923), chemist
Lagrange;Lagrange, Joseph-Louis: 1736 to 1813, mathematician
Lahmeyer;Lahmeyer, Wilhelm: 1859 to 1907, electrical engineer and industrialist
Lambert;Lambert, Jahann Heinrich: 1728 to 1777, mathematician and physicist
Lampadius;Lampadius, Wilhelm August: 1772 to 1842, chemist and technologist
Land;Land, Edwin Herbert (1909-1991), American physicist
Landau;Landau, Lev Davidovich: 1908 to 1968, physicist
Lands;In laser discs such as CDs or DVDs lands mean the flat areas of a track. The data units, read by a laser beam are stored in microscopic depressions in the surface called pits.
Langen;Langen, Eugen: 1833 1895, engineer
Langmuir;Langmuir, Irving: 1881 to 1957, physicist and chemist
Laplace;Laplace, Pierre-Simon: 1749 to 1827, mathematician and astronomer
Latour;Latour, Charles Cagniard: 1777 to 1859, engineer and geographer
Laue;Laue, Max von: 1879 to 1960, physicist
Laurent;Laurent, Auguste: 1807 to 1853, chemist
Laval;Laval, Carl Gustav de: 1845 to 1913, engineer
Lavoisier;Lavoisier, Antoine-Laurent: 1743 to 1794, chemist
Lawrence;Lawrence, Ernest Orlando: 1901 to 1958, physicist
Lear;Lear, William P.: 1902 to 1978, radio engineer
Lebedev A.;Lebedev, Aleksander Alekseyevich: 1893 to 1969, chemist
Lebedev P.;Lebedev, Piotr Nikolayecich: 1866 to 1912,Physicist
Lebedev S.;Lebedev, Sergei Vasilyevich: 1874 to 1934, chemist
Leblanc;Leblanc, Nicolas: 1742 to 1806, physician and chemist
Lebon;Lebon, Philippe: 1769 to 1804, engineer
LeChatelier;LeChatelier, Henry-Louis: 1850 to 1936, chemist and engineer
Lecher;Lecher, Ernst: 1856 to 1926, physicist
Ledebur;Ledebur, Adolf: 1837 to 1906, iron and steel expert
Ledley;Ledley, Robert S.: (* 1926), biophysicist
Leech rope;A boltrope is a rope hemming sewn around every sail made of cloth. 
Leeuwenhoek;Leeuwenhoek, Antony van (1632-1723), Dutch naturalist
Leibnitz;Leibnitz, Gottfried Wilhelm: 1646 to 1716, Universal scholar
Lenard;Lenard, Philippe: 1862 to 1947, physicist
Lenoir;Lenoir, Jean Joseph Etienne (1822-1900), Luxeembourgeois engine manufacturer
Lens;An objective lens is a lens assembly in an optical instrument such as a camera or telescope. It faces the subject of a picture.
Lenz;Lenz, Heinrich Friedrich Emil: 1804 to 1865, physicist
Leslie;Leslie, John: 1766 to 1832, physicist
Leupold;Leupold, Jacob1674 to 1726, precision engineer
Levasseur;Levasseur, Léon:1863 to 1922, aircraft designer
Lever;A lever is a power transmission device, in which an object, usually consisting of a straight or bent rod, is pivoted on a fulcrum.
Lever principle;The lever principle states that the effort is exerted in an inverse ratio of the distance from the fulcrum to the load. 
Leverage;Leverage is based on the principle that a relatively large force can be produced on the shorter lever arm by exerting less effort on the longer lever arm.
Lichtenberg;Lichtenberg, Georg Christoph: 1742 to 1799, physicist and writer
Lieben;Lieben, Robert von: 1878 to 1913, physicist and engineer
Liebermann;Liebermann, Karl: 1842 to 1914, chemist
Liebig;Liebig, Justus von: 1803 to 1873, chemist
Lift;Lift, upward vertical force exerted on an object. 
Light year;Distance that light covers in a year (around 9,500 billion kilometers).
Lilienthal;Lilienthal, Otto: 1848 to 1896, aviation pioneer
Linde;Linde, Carl von: 1842 to 1934, engineer
Links;A hypertext link is a cross-reference between files. Hyperlinks or jump links are currently used extensively in connection with data structures on the Internet or in multimedia programs. They enable users to access further information (hyperlink) by merely clicking on a word or a picture.
Lippershey;Lippershey, Johannes: 1572 to 1640, optician
liquid propellant;Liquid fuel for rockets usually consists of liquid hydrogen and liquid oxygen.
Lissajous;Lissajous, Jules-Antoine: 1822 to 1880, physicist
Lister;Lister, Sir Joseph: 1827 to 1912, physician
Ljupunov;Lyupunov, Aleksander Mikhailovich: 1857 to 1918, mathematician
Llyushin;Ilyushin, Sergey Vlademirovich: 1894 to 1977, aircraft designer
Load;Load may either mean an object that needs carrying or a force that is exerted through the weight of a load (e.g. on a crane). 
Lodge;Lodge, Sir Oliver Joseph: 1851 to 1940, physicist
Lodygin;Lodygin, Aleksander Nikolayevich: 1847 to 1923, engineer
Loewe;Loewe, Ludwig: 1837 to 1886, engineer
Log-in;Logging in involves requesting and being allowed the access to a system such as a network or mailbox.
Lomonossov;Lomonossov, Mikhail Vasilyewich: 1711 to 1765, scholar
Lorentz;Lorentz, Hendrik Antoon: 1853 to 1928, physicist
Loschmidt;Loschmidt, Joseph: 1821 to 1895, physicist
Lüdemann;Lüdemann, Karl-Friedrich: 1912 to 1967, metallurgist
Luff Rope;A boltrope is a rope hemming sewn around every sail made of cloth. This rope is sewn with flat stitches on the edge of the sail.
Lumière;Lumière, Auguste: 1862 to 1954, chemist