👻 pitṛtantra

The term pitṛtantra (for Tibetan pha’i rgyud or pha rgyud) is, in my view, a ghost word. This, however, does not mean that also Tibetan pha’i rgyud or pha rgyud is a ghost word. The Tibetan pha’i rgyud or pha rgyud is an abbreviated or elliptical expression for rnal ’byor pha’i rgyud and is actually a rendering of yogatantra. In Tibetan it would be quite legitimate to translate yogatantra as rnal ’byor pha’i rgyud especially when there is a need to distinguish it from yoginītantra, just as it is quite common to render bhikṣuvibhaṅga as dge slong pha’i rnam ’byed, which in turn has often be abbreviated as pha’i rnam ’byed.

👻 mātṛtantra

The term mātṛtantra (for Tibetan ma’i rgyud or ma rgyud) is, in my view, a ghost word. This, however, does not mean that also Tibetan ma’i rgyud or ma rgyud is ghost word. The Tibetan ma’i rgyud or ma rgyud is an abbreviated or elliptical expression for rnal ’byor ma’i rgyud and is actually a rendering of yoginītantra. In Tibetan it would be quite legitimate to translate yoginītantra as rnal ’byor ma’i rgyud especially when there is a need to distinguish it from yogatantra, just as it is quite common to render bhikṣuṇīvibhaṅga as dge slong ma’i rnam ’byed, which in turn has often be abbreviated as ma’i rnam ’byed. 

👻 cittamātrin

The term cittamātrin is said to be not attested in Sanskrit sources. Note, however, that the term cittamātravādin is attested. 

👻 dhyāni-buddha

Sanskritists would agree, I am sure, that dhyāni-buddha is certainly to be treated as a ghost Sanskrit word.

👻 dhāraṇīpiṭaka

I contend that dhāraṇīpiṭaka is a ghost Sanskrit word. The term vidyādharapiṭaka, however, is well-attested. We shall have to trace the term mantrapiṭaka (gsang sngags kyi sde snod) in Sanskrit sources.