Anhypostasia

[H]e [Henry Liddon] observes, "The anhypostasia (impersonality) of our Lord's humanity is a result of the hypostatic union: to deny it is to assert that there are two persons in Christ, or else deny that he is more than man. At his Incarnation, the Eternal Word took on him human nature, not a human personality."

Source: wiktionary

The doctrine of the person of Christ is argued with greatest fullness, and he [John of Damascus] evinces no little ingenuity and dialectic skill in treating of the personal unity in Christ's twofold nature (which he conceived as enhypostasis, not anhypostasis, of the human nature in the Logos), […]

Source: wiktionary

By anhypostasia classical Christology asserted that in the assumptio carnis the human nature of Christ had no independent per se subsistence apart from the event of the incarnation, apart from the hypostatic union. By enhypostasia, however, it asserted that in the assumptio carnis the human nature of Christ was given a real and concrete subsistence within the hypostatic union—it was enhypostatic in the Word. Anhypostasia and enhypostasia are inseparable. In the incarnation the eternal Son assumed human nature into oneness with Himself, but in that assumption Jesus Christ is not only real man but a man.

Source: wiktionary

‘Anhypostasia’ describes the conviction that the human nature of the incarnate Christ did not have a personal centre of subsistence, but was rather incorporated into the person of the eternal Word with which it was united at the incarnation. […] Thus ‘anhypostasia’ is a way of articulating the fact that Jesus is, as it were, so totally taken up with his proclamation of the Kingdom of God that his whole being could be defined by reference to that Kingdom.

Source: wiktionary