Gertrude f. Old High German, Old Saxon gēr 'spear' + Proto-Germanic *þrūþ 'strength' or Proto-Germanic *trut 'maiden'.
The name of two 7th C saints and a 13th C German saint, a 12th C queen consort of Denmark, a 13th C queen consort of Germany, and a 13th C queen consort and later regent of Hungary.