Ananda Mahidol
"Ananda Mahidol" () is one word in Thai and is his given name. King Vajiravudh, his uncle, sent a telegram on 13 October 1925 giving him this name. It is pronounced "Ananta Mahidon" and means "the joy of Mahidol". When he held his birth rank of Mom Chao—the lowest rank of Thai princes—he used the surname "Mahidol", his father's given name. His full name and title was thus, "Mom Chao Ananda Mahidol Mahidol" ().