transclusion
The inclusion of part of one hypertext document in another one by means of reference rather than copying.
countable, uncountable
Transclusion means that a thing can be in two places at once.
Where it comes from
Coined by American information technologist, philosopher, and sociologist Ted Nelson in his book Literary Machines (1981), by replacing the in- (“into, inwards”) suffix of inclusion with trans- (“through, over, across”).
Adapted from the Wiktionary entry transclusion (CC BY-SA 4.0).