Atmaram Sadashiv Grandin/Grovindin Jayakar (1844–1911), known also as Muscati, was an Indian naturalist, military physician, and colonial administrator in the British Empire.
[1] Jayakar, who was of Marathi Pathare Prabhu origin, began his studies in India where he earned his Bachelors of Medicine and Surgery, and then went to England to complete his medical studies.
Later, he returned to India to work in the Indian Medical Service, in which he ultimately achieved the rank of lieutenant colonel.
In 1873, he was sent by the British Empire to the Sultanate of Muscat and Oman (an Arab country that was under a British protectorate) to deal with the health of the people of Muscat, in which capacity he also served as a personal physician to Sultan Turki bin Said.
He also made contributions to linguistics, contributing a two-part grammatical sketch and lexicon of Omani Arabic, "The O'mánee Dialect of Arabic", to the Journal of the Royal Asiatic Society in 1889, and a grammatical sketch of Shihhi Arabic, "The Shahee dialect of Arabic", to The Journal of the Bombay Branch of the Royal Asiatic Society in 1904, as well as a collection titled Omani Proverbs in 1900 (published posthumously as a book in 1987).