The term 'Doctor-Turned-Wordsmith' refers to Peter Mark Roget, a British physician and lexicographer who is best known for his thesaurus. Roget was born in 1779 and studied medicine at the University of Edinburgh. After graduating, he worked as a doctor for several years before turning his attention to writing. He published his first thesaurus in 1852, which was an alphabetical list of English words and their synonyms. The book was an instant success and has since been revised and updated numerous times. Roget's name is now synonymous with the thesaurus, and his legacy lives on in the form of the five-letter word 'ROGET'.