Clauson (1972)
An etimological dictionary of pre-thirteenth-century Turkish
p. 46
D ıḏuk
Dev. Pass. N./A.S. fr. ı:ḏ-; lit. ‘sent’, but used only in the sense of ‘sent, i.e. dedicated, to God’, hence ‘sacred’ in a more general sense; the phr. ıḏuk kut ‘the sacred favour of heaven’ was early adopted as a royal title by some tribes; in course of time its origin was forgotten, and in San. it is spelt idi kut and given a false etymology (see 1 idi:). Survives in some distorted forms ıyık, i:k, izik, etc. in NC, and SW xx Anat. SDD 777, 1098. Türkü viii (the Türkü divinity on high thus set in order) türkü ıḏuk yeri: suvı: ‘the sacred Türkü territory’ I E 10, II E 10; ıḏuk yer suv II E 35; T 38: ıḏuk Ötüken yış ‘the sacred Ötüken mountain forest’ I E 23, II E 19; Bismil ıḏuk(k)ut ‘the Iduk kut of the Basmıl’ II E 25; ıḏuk baş a place name; ıḏuk baş kedinte: ‘west of Iduk Baş’ Şu. E 9: viii ff. Man. ıḏuk kaŋımız ‘our saintly father’ TT III 18, 20; do. 57, 1; ıḏuk kut ‘our king the Iduk kut’ M III 35, 9, 14 and 19; ıḏuk örgin ‘the sacred throne’ do. 35, 18: Bud. ıḏuk ‘sacred’ Suv. 149, 3; 447, 15; USp. 43, 8: Civ. USp. 40 and 41 are documents of a late period addressed to Iduk kut teŋrikenimiz: O. Kır. ix ff. öz yerim ıḏuk yerim ‘my own land, my sacred land’ Mal. 42, 1: Xak. xi ıḏuk kull şay’ mubārak ‘anything blessed’; its origin is that any animal which is set free (yusayyab) is called ıḏuk; its back is not loaded nor its udders milked nor its fleece shorn because of a vow incumbent on its owner: ıḏuk ta:ğ al-cabalu’l-māni‘u’l-ṭawīl ‘an inaccessible long mountain’ Kaş. I 65: KB ıḏuk kut ‘the blessed favour of heaven’ (not as a title) is fairly common, 343, 354, 1335, etc.; ıḏuk also occurs in other contexts, e.g. of beglik 1960: xiv Muh.(?) al-qaḍā wa’l-qadar ‘destiny, fate’ iyi:k Rif. 189.