御孫さん[omagosan] grandchild
公孫樹[kousonju] ginkgo (Ginkgo biloba)
玄孫[genson] great-great-grandchild
子孫[shison] descendants
児孫[jison] children and grandchildren

孫引き[magobiki] citation at second remove
孫息子[magomusuko] grandson
孫娘[magomusume] granddaughter
嫡孫[chakuson] eldest son's descendants