(Greek: an emptying)
Saint Paul (Philippians 2) says of Christ that He "emptied Himself."
This emptying of self is to be properly understood of the abasement involved in the fact of the Incarnation, wherein the Second Person of the Trinity, retaining in the full sense His Godhead, assumed a lower nature with its limitations and imperfections.
Often wrongly interpreted to mean that the Second Person voluntarily surrendered, for the time being, certain divine attributes which seemed incompatible with existence on a human plane.
New Catholic Dictionary