Christ is the only (or uniquely) begotten Son of God. From eternity. It is absolutely biblical and here's the proof: But thou, Bethlehem Ephratah, though thou be little among the thousands of Judah, yet out of thee shall he come forth unto me that is to be ruler in Israel; whose goings forth have been from of old, from everlasting. (Micah 5:2) This prophecy applies to Christ.Jesus Christ was begotten, conceived in Mary by God. “Eternally begotten” is not biblical.
EVERLASTING = ETERNAL