初うい孫まごalso: はつまごういまごFreq.FrequencyTop 100,000Meanings1nounfirst grandchildRefers to the first grandchild born into a family, often a momentous occasion.両りょう親しんは初うい孫まごの誕たん生じょうをとても喜よろこんだ。My parents were overjoyed at the birth of their first grandchild.