From Persianکتاب اقدس (ketâb-e aqdas, in Baháʼí transliteration Kitáb-i-Aqdas, literally “the holiest book”), from Arabicكِتاب(kitāb, “book”) + أَقْدَس(ʔaqdas, “holiest, exceedingly holy”), the latter word being elative of قِدِّيس(qiddīs) or قُدُّوس(quddūs), both “holy”.