There are four theories about its origin:
- Either from Old High German kenning (“symbol, sign”) or from a different Germanic source (compare Gothic 𐌺𐌿𐌽𐌽𐌰𐌽 (kunnan, “to know”) and Old Norse kunna (“to know”)).
- Alternatively, from Akkadian 𒁾 (kunukku, “seal-cylinder, kunukku”) or [script needed] (kanikku, “sealed object: document, sack bulla, etc.”), via Old Armenian կնիք (knikʿ, “seal”) and Turkic.
- A Chinese origin, from 卷 (Middle Chinese /kɣiuᴇnX, kɣiuᴇnH/ < Old Chinese /*krorʔ/ ("to roll up"), /*kror-s/ ("scroll")) via Proto-Turkic *küiniŋ, has also been suggested, as paper was invented in China in about the 1st century AD. However this seems less likely, due to the likely temporal precedence of Proto-Slavic over Early Middle Chinese and the large spatial separation of the donor and recipient languages. Speaking in favor of this etymology is, however, Hungarian könyv (“book”) (reflecting hypothetical Pre-Hungarian *künig), which is much more clearly derived from Turkic *küiniŋ and cannot be derived from the Slavic forms.
- Finally, Polish Slavicist Aleksander Brückner considers it to be a native word derived from Proto-Slavic *kъnъ (“trunk of a tree”) with the suffix -iga (compare Slovene veriga (“chain”), from Proto-Indo-European *ver- (“tie”)). The sense development would thus be similar to German Buch and English book, from Proto-Indo-European *bʰeh₂ǵos (“beech”), or to Latin liber, from earlier *luber, a cognate of Proto-Slavic *lubъ (“tree bark”).
Declension of *kъnjiga (hard a-stem)
- East Slavic:
- South Slavic:
- West Slavic:
- “книга” in Max Vasmer (1986), Etimologičeskij slovarʹ russkovo jazyka [Etymological Dictionary of the Russian Language], in 4 vols (second edition), Moscow: Progress — Translated from German and supplemented by O. N. Trubačóv
- “*kъniga” in Oleg Trubačóv (ed.) (1974–), Etimologičeskij slovarʹ slavjanskix jazykov [Etymological dictionary of Slavic languages], Moscow: Nauka, volume 13, page 203f
- “книга” in Galina Cyganenko (1989), Etimologičeskij slovarʹ russkovo jazyka [Etymological Dictionary of the Russian Language], (2nd ed.), Kiev: Radyanska Shkola, page 179–180
- “книга” in Pavel Černyx (1999), Istoriko-etimologičeskij slovarʹ russkovo jazyka [Historical-Etymological Dictionary of the Russian Language], in 2 vols (3rd ed.), Moscow: Publishing House "Russian Language", volume 1, page 406
- “ḱinyg | kinugæ, kiwnugæ” in Vasilij Abajev (1958–89), Istoriko-etimologičeskij slovarʹ osetinskovo jazyka [Historical-Etymological Dictionary of Ossetian], in 4 vols, Moscow–Leningrad: USSR Academy of Sciences, volume 1, page 596
- “կնիք” in Hračʿeay Ačaṙean (1971–79), Hayerēn armatakan baṙaran [Dictionary of Armenian Root Words], in 4 vols (second edition), Yerevan: Yerevan State University [Reprint of the original edition: 1926–1935, in 7 volumes, Yerevan], volume 2, page 609