Definition of protosolar in US English:

protosolar

adjective

Astronomy
  • Of or relating to the protosun.

Origin

1960s; earliest use found in Proceedings of the National Academy of Sciences of the United States of America. From proto- + solar, probably after protosun.

Pronunciation

protosolar

/ˌprəʊtə(ʊ)ˈsəʊlə/