One of the mysteries of the English language finally explained.
With reference to an action or characteristic of God which is not communicable to the world beyond the Persons of the Trinity. Also more generally: with effect or result only in one's own mind, self, etc. (rather than in the outside world); within, internally. Opposed to ad extra.
Designating an action or characteristic of God that is not communicable beyond the Persons of the Trinity. Also more generally: designating an action that does not have an effect or result in the outside world; imperceptible, internal, interior. Opposed to ad extra.
Early 17th century; earliest use found in John Boys (d. 1625), dean of Canterbury. From post-classical Latin ad intra towards the inside from classical Latin ad to, towards + without object.
ad intra/ˌad ˈɪntrə/
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