"Tirodhana" is one of the purely PanchaRatrika notions, that's why OM VishnuPad Shree RamanujAcharya mentions it in "Shree Bhagavad-Gita". The phrase by OM VishnuPad Shree RamanujAcharya is hard to translate from the elegant Sanskrit into rather clumsy English, but if to convey the idea, then - "The concealment of Divine nature" (yes, sounds not as charming as the original Sanskrit phrase!).
The blue-green screenshot-quote is from - http://shodhganga.inflibnet.ac.in/handle/10603/59671
