Citations:knot

Sense: A group of people or things

 * 1843 — Charles Dickens. A Christmas Carol.
 * The Spirit stopped beside one little knot of business men. Observing that the hand was pointed to them, Scrooge advanced to listen to their talk.

Sense: nautical mile

 * 1821, Nathaniel Bowditch, The New American Practical Navigator, p. 89
 * Thus, if a ship sails 6 knots per hour, with a glass of 24 seconds, and a log-line of 60 feet per knot, her true velocity will be 9 miles per hour...
 * 1845, The Mechanics Magazine, vol. 42, p. 23.
 * Off Woolwich we put the vessel ender sail, and with the sails alone, and the propeller detached, made about 4 knots per hour;
 * 1896, Annie Brassie, The Last Voyage, to India and Australia, in the Sunbeam, p. 463
 * On the day before the arrival at Adelaide the distance of 265 knots was made good;
 * 1897, A. P. Trotter, "Disturbance of submarine cable working by electric tramways", Journal of the Institution of Electrical Engineers, vo. 26, p. 504.
 * I am informed that the length is 1,383.526 knots and the resistance 8,820 ohms.
 * 1945, Pacific Marine Review, vol. 42, p. 348
 * To find the new total fuel used for 2000 knots steaming...
 * 2009. "Apollo-era life rafts save hundreds of sailors", Spinoff, pp. 70-71, NASA Center for AeroSpace Information, ISBN 0160841917.
 * With winds gusting to 190 knots per hour, their 30-ton ketch capsized...

I've removed the labels slang and incorrrect from this term. The cites are mostly from reputable and knowledgable sources, making it unlikely that this is either slang or considered incorrect, at least, not historically. The earliest cite is from Nathaniel Bowditch, a mathematician, Fellow of the Royal Society, and Doctor of Law, writing in a mathematical text for navigators. Bowditch doesn't strike me as a person who uses slang or imprecise language. Bowditch's book has been continuously updated and is still a current text for training naval officers. The term "knots per hour" was still being used in the 1916 edition, the latest free-to-read edition available online. From the ngram for knots an/per hour the peak usage of this sense occured around 1890. Comparing with all occurences of knots, this is over 12% of the total, a staggering result considering how common a word this is. And "knots per hour" is not the only usage of this sense; "a distance of x knots" also occurs, so the true percentage is likely much higher.

I do get the pedantic argument that "knots per hour" is redundant repetition because a knot is already a nautical mile per hour. But it is at least arguable that the incorrect usage is the other way around. The original meaning was the distance between knots on the log line; a measure of distance, not of speed. 120 of these "small" knots is equal to a "big" knot, or a nautical mile. With that logic, "x knots per hour" is correct and "a speed of x knots" is a sloppy contraction.  Spinning Spark  12:24, 17 September 2019 (UTC)

Sense: (fandom slang) a bulbus glandis-like structure on the penis of a male alpha

 * 2013, Kristina Busse, "Pon Farr, Mpreg, Bonds, and the Rise of the Omegaverse", in Fic: Why Fanfiction Is Taking Over the World (ed. Anne Jamison), page 317:
 * Animal terminology, such as heat, mating cycles, claiming, mounting, breeding, and the ever-popular knot, tends to be popular in A/B/O stories.
 * 2014, Mark Shrayber, "'Knotting' Is the Weird Fanfic Sex Trend That Cannot Be Unseen", Jezebel, 18 July 2014:
 * Since the knot won't release until the alpha has finished and can't be controlled by either party, the sex has to go on until it's done.
 * 2017, Taylor Boulware, "Fascination/Frustration: Slash Fandom, Genre, and Queer Uptake", dissertation submitted to the University of Washington, page 155:
 * The pair cannot separate until the knot has subsided – anywhere from twenty minutes to hours, depending on the fic.
 * 2017, Elliot Aaron Director, "Something Queer in His Make-Up: Genderbending, Omegaverses, and Fandom's Discontents," dissertation submitted to Bowling Green State University, page 137:
 * The Alpha is unable to force their "knot" to lessen or subside, and so upon the Alpha's orgasm, the Alpha/Omega couple become physically locked together, often for several hours,until the former's "knot" becomes small enough to be withdrawn from the Omega's body.
 * 2017, Marianne Gunderson, "What is an omega? Rewriting sex and gender in omegaverse fanfiction", thesis submitted to the University of Oslo, page 89:
 * When John bites down on Sherlock's neck as his knot locks them together, the act which would otherwise be a tool for domination only reinforces the existing emotional bonds they have for each other.
 * 2017, Joanna Lamstein, "Not Safe for Women: Asserting Control Over Trauma Through Fan Fiction", thesis submitted to San Francisco State University, page 31:
 * Alphas usually have knots (a swelling of the base of the penis to keep them locked with their sexual partner during sex, based from canines), and betas are usually humans as we typically think of them in terms of reproductive capacities.
 * 2018, Laura Campillo Arnaiz, "When the Omega Empath Met the Alpha Doctor: An Analysis of Alpha/Beta/Omega Dynamics in the Hannibal Fandom", in The Darker Side of Slash Fan Fiction (ed. Ashton Spacey), page 127:
 * The mating process is described in excruciating detail; Hannibal disrobing Will, feasting on his young, virgin body, enjoying Will's tears from the pain of the first penetration and biting him forcefully on the nape when the boy can't take his knot—until Will finally submits.