կոյս

Probably an Iranian borrowing, but the details are uncertain. Likely from the family of Persian کس (kos, “pussy”) and Persian کشتی (kusti, košti, “sacred girdle”), and so related to Etymology 2 bellow. Alternatively, from the family of Classical Persian کوسه (kōsa, “man with little or no beard”).

կոյս • (koys)

1. virgin, maiden, unmarried girl

   կոյս դեռահասակ ― koys deṙahasak ― young virgin, girl, maid

2. (Christianity) the Holy Virgin
3. (astronomy) Virgo

կոյս • (koys)

1. virgin, virginal, maiden, maidenly
2. pure, chaste (of a girl or young man)
3. uncontaminated, untouched, unmingled, inviolate (of things)

   կոյս ճանապարհ ― koys čanaparh ― untrodden path

   կոյս գերեզման ― koys gerezman ― empty tomb

4. mysterious, secret, hidden (of things)

   կոյս թիւ ― koys tʻiw ― the number seven

• Armenian: կույս (kuys)
• → Georgian: კუსი (ḳusi), ყუსი (q̇usi)

• Ačaṙean, Hračʻeay (1973) “կոյս”, in Hayerēn armatakan baṙaran [Armenian Etymological Dictionary] (in Armenian), 2nd edition, a reprint of the original 1926–1935 seven-volume edition, volume II, Yerevan: University Press, pages 629–630
• Awetikʻean, G., Siwrmēlean, X., Awgerean, M. (1836–1837) “կոյս”, in Nor baṙgirkʻ haykazean lezui [New Dictionary of the Armenian Language] (in Old Armenian), Venice: S. Lazarus Armenian Academy
• Gippert, Jost (1993) Iranica Armeno-Iberica: Studien zu den iranischen Lehnwörtern im Armenischen und Georgischen (Österreichische Akademie der Wissenschaften. Philosophisch-historische Klasse. Sitzungsberichte; 606. Veröffentlichungen der Kommission für Iranistik; 26)‎ (in German), volume I, Vienna: Verlag der Österreichischen Akademie der Wissenschaften, pages 165–166
• J̌ahukyan, Geworg (1979) “Stugabanutʻyunner [Etymologies]”, in Lraber Hasarakakan Gitutyunneri [Herald of the Social Sciences]‎ (in Armenian), number 3, Yerevan: Academy Press, page 27 of 23–34, deriving from Hittite (kūša-, “in-law; bride”)
• Olsen, Birgit Anette (1999) The noun in Biblical Armenian: origin and word-formation: with special emphasis on the Indo-European heritage (Trends in linguistics. Studies and monographs; 119), Berlin, New York: Mouton de Gruyter, page 298
• Pedersen, Holger (1907) “Neues und nachträgliches”, in Zeitschrift für vergleichende Sprachforschung auf dem Gebiete der Indogermanischen Sprachen‎ (in German), volume 40, number 2, pages 197–198
• Pedersen (Pedersən), Holger (1907) H. Tʻovmas Ketikean, transl., Hayerēn ew dracʻi lezunerə [Armenian and the Neighbouring Languages] (in Armenian), Vienna: Mekhitarist Press, page 204
• Petrosean, Matatʻeay (1879) “կոյս”, in Nor Baṙagirkʻ Hay-Angliarēn [New Dictionary Armenian–English], Venice: S. Lazarus Armenian Academy
• Sims-Williams, Nicholas (1979 February) “A Parthian sound-change”, in Bulletin of the School of Oriental and African Studies‎, volume 42, number 1, →DOI, pages 133–136

An Iranian borrowing: compare Parthian 𐫐𐫇𐫘 (kws /⁠kōs⁠/, “district, region, countryside”), Sogdian (kws, “side”).

կոյս • (koys)

1. side

   ընդ ո՞ր կոյս ― ənd o^?r koys ― which way? where?

   ի կուսէ անտի ― i kusē anti ― on that side or part

   յամենայն կուսաց ― yamenayn kusacʻ ― on all sides

   յոր կոյս եւ կամիցի ― yor koys ew kamicʻi ― wherever he pleases

   յայս կոյս յայն կոյս ― yays koys yayn koys ― from one side to another, on one side and the other, here and there

   զգնալ յայս կոյս եւ յայն կոյս ― zgnal yays koys ew yayn koys ― to take a walk hither and thither, to and fro

   յայս կոյս յայն կոյս գետոյն ― yays koys yayn koys getoyn ― on this side and on that of the river, here and there

   յայն կոյս ծովուն ― yayn koys covun ― beyond the sea

   ի թիկունս կոյս, յետս կոյս ― i tʻikuns koys, yets koys ― behind one's back, behind, from behind

   յարեւելից կուսէ ― yarewelicʻ kusē ― from the East

   յարեւմուտս կոյս ― yarewmuts koys ― towards the West

   ի կայս եւ ի կոյս կողմանց հիւսիսոյ ― i kays ew i koys kołmancʻ hiwsisoy ― towards the North

   ի հարաւակողմն կուսէ ― i harawakołmn kusē ― from the South

   ի մէնջ կուսէ ― i mēnǰ kusē ― for us, for our part, as for us

   ի մեր կոյս է ― i mer koys ē ― he is on our side, he is favourable to us

   ոմն ի սորա կոյս, եւ ոմն ի նորա ― omn i sora koys, ew omn i nora ― one maintained this and another that

   կոյս մի ընդ միոյ կուսին ընդհարեալ ― koys mi ənd mioy kusin əndhareal ― one side fought with the other

   ի կատարածն կոյս թղթիս ― i kataracn koys tʻłtʻis ― towards the end of my letter

   ելանել ի բացեայ կոյս ― elanel i bacʻeay koys ― to retire aside

   ի չորս կոյս վիմաց ― i čʻors koys vimacʻ ― of hewn stone

• Armenian: կույս (kuys)

• Ačaṙean, Hračʻeay (1973) “կոյս”, in Hayerēn armatakan baṙaran [Armenian Etymological Dictionary] (in Armenian), 2nd edition, a reprint of the original 1926–1935 seven-volume edition, volume II, Yerevan: University Press, page 630ab
• Awetikʻean, G., Siwrmēlean, X., Awgerean, M. (1836–1837) “կոյս”, in Nor baṙgirkʻ haykazean lezui [New Dictionary of the Armenian Language] (in Old Armenian), Venice: S. Lazarus Armenian Academy
• Martirosyan, Hrach (2010) Etymological Dictionary of the Armenian Inherited Lexicon (Leiden Indo-European Etymological Dictionary Series; 8), Leiden and Boston: Brill, pages 370–371
• The template Template:R:xcl:Jahukyan:1995 does not use the parameter(s):

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  Please see Module:checkparams for help with this warning.J̌ahukyan, Geworg (1995) “Hay-iranakan lezvakan zugadipumner [Armenian–Iranian Lingual Parallels]”, in Patma-banasirakan handes [Historical-Philological Journal]‎ (in Armenian), number 2, pages 183–186
• Petrosean, Matatʻeay (1879) “կոյս”, in Nor Baṙagirkʻ Hay-Angliarēn [New Dictionary Armenian–English], Venice: S. Lazarus Armenian Academy
• Sims-Williams, Nicholas (1979 February) “A Parthian sound-change”, in Bulletin of the School of Oriental and African Studies‎, volume 42, number 1, →DOI, pages 133–136