[pro.to.plan.et] n (1949): a hypothetical whirling gaseous mass within a giant cloud of gas and dust that rotates around a sun and is believed to give rise to a planet -- pro.to.plan.e.tary adj
PROTOPLANET
Meaning of PROTOPLANET in English
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012