protomoon

The central volume of the protomoon is largely or wholly lost; material retained in orbit originally occupied positions relatively near the surface of the protomoon.

1974, JA Wood, HE Mitler, “Origin of the Moon by a modified capture mechanism, or half a loaf is better than a whole one”, in Abstracts of the Lunar and Planetary Institute, adsabs.harvard.edu

If the Moon was formed during the Earth's accretion, a subsequent accretion of residual heliocentric planetesimals onto the protoearth and the protomoon must have occurred. In this co-accretion stage, a significant amount of lunar-impact-ejecta would be ejected to circumterrestrial orbits, since the mean impact velocity of the planetesimals with the protomoon is much larger than the escape velocity of the protomoon.

2004 March 29, Ryuji Morishima, Sei-ichiro Watanabe, “Co-accretion of the Earth–Moon system after the giant impact: reduction of the total angular momentum by lunar impact ejecta”, in Icarus, volume 168, number 1, pages 60-79