Definition of "Q"

Q¹

letter
upper case, lower case q, plural Qs or Q's
1. The seventeenth letter of the English alphabet, called cue and written in the Latin script.
number
upper case, lower case q
1. The ordinal number seventeenth, derived from this letter of the English alphabet, called cue and written in the Latin script.

Q²

noun
1. Abbreviation of question or questions.
2. Abbreviation of quarter.
3. (electronics) Short for Q factor (“quality factor”).
4. (astronomy) Abbreviation of quasar.
5. (sports) Abbreviation of qualified.
6. American Library Association abbreviation of quarto (“book size”).
7. (card games, chess) Abbreviation of queen.
8. (medicine) Alternative letter-case form of q (“every”).
proper noun
1. (literature, pseudonym) Arthur Quiller-Couch.
2. (Islam, followed by an ayah (verse) number) Abbreviation of Quran.
3. (theology, Christianity) The hypothetical common source (logion collection) of the Gospels of Matthew and Luke (from German Quelle (“source”)); all the non-Marcan shared material in those gospels (not always considered a single document)
  Quotations
  In comparing Q 10:10–11 and Mark 6:11, there is no reliable way to determine which exact form of the saying is more primitive, the third person account of Mark or the direct speech recorded in Q.
  2006, Brian Han Gregg, The Historical Jesus and the Final Judgment Sayings in Q, Mohr Siebeck, page 103
4. (US politics) Abbreviation of QAnon (“anonymous poster on anonymous online message boards”).
  Quotations
  In this fantasy world, all of the far right’s wildest dreams come true: Q promises that Clinton, Obama, Podesta, Abedin, and even McCain are all either arrested and wearing secret police-issued ankle monitors, or just about to be indicted; that the Steele dossier is a total fabrication personally paid for by Clinton and Obama; and that the Las Vegas massacre was most definitely an inside job connected to the Saudi-Clinton cabal.
  2017 December 19, Paris Martineau, “The Storm Is the New Pizzagate — Only Worse”, in New York‎, archived from the original on 26 December 2018
  In a thread called “Calm Before the Storm”, and in subsequent posts, Q established his legend as a government insider with top security clearance who knew the truth about a secret struggle for power involving Donald Trump, the “deep state”, Robert Mueller, the Clintons, pedophile rings, and other stuff.
  2018 July 31, Julia Carrie Wong, “What is QAnon? Explaining the bizarre rightwing conspiracy theory”, in The Guardian‎
  At the end of her report, Coaston concluded, “Most people have never heard of QAnon, or Q — and that includes most of Donald Trump’s supporters.” That’s still the case, but the fact that this book is at the top of some of Amazon’s most prominent recommendation lists means that a far larger share of the population will — at a minimum — stumble across these ideas.
  2019 March 6, Kaitlyn Tiffany, “How a conspiracy theory about Democrats drinking children’s blood topped Amazon’s best-sellers list”, in Vox‎, archived from the original on 7 March 2019

Q³

noun
plural Qs
1. (slang) A gadget master, gadget creator.