Princess Adelaide "Adi" of Saxe-Meiningen (Adelaide Erna Caroline Marie Elisabeth; later Princess Adalbert of Prussia; 16 August 1891 – 25 April 1971) was a daughter of Prince Frederick John of Saxe-Meiningen and his wife Countess Adelaide of Lippe-Biesterfeld.

Adelaide (original German: Adelheid)'s father Prince Frederick was a younger son of George II of Saxe-Meiningen by his second wife Feodora of Hohenlohe-Langenburg. She had five siblings, including Prince George, a prisoner of war killed during World War II, and Prince Bernard.

Adelaide's mother, also named Adelaide, was the eldest child of Ernst, Count of Lippe-Biesterfeld, who was the Regent of the principality of Lippe for seven years (1897–1904).

On 3 August 1914, at the beginning of World War I, Adelaide married Prince Adalbert of Prussia at Wilhelmshaven, Schleswig-Holstein, Germany. He was the third son of Kaiser William II of Germany. Adelaide's father would die within a month, on 23 August 1914. Less than a month after their marriage, Prince Adalbert was reported to have been killed in battle in Brussels. This was only a rumor however, and the prince had been unharmed. In March 1915, he was promoted to Captain in the navy and Major in the army.

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