(g, g)  [Turk. agh master.] 

    1. In Muslim countries (esp. under the Ottoman empire): a commander or chief officer; originally a military title, but used also of civil officers and as a title of distinction.
 
  1600 PORY Leo's Hist. Africa 386 Neither can they be judged by any but the Agaes. 1628 DIGBY Voy. to Medit. (1868) 15 The Agaw, the principall officer next to the Bassa. 1667 Lond. Gaz. cxxxv/2 The Aga of the Janisaries in quality of paymaster to the Army. 1865 Daily Tel. 6 Nov. 5/5 The different tribes..and the aghas who are to command them.
 

    2. Aga Khan [KHAN¹], the title successively adopted by the spiritual leader or imam of the Khoja branch of Ismaili Muslims. Also fig.
 
  1842 H. C. RAWLINSON Let. 6 Mar. in Parl. Papers 1843 XXXVII. 217 The Persian refugee, Agha Khan, is still a guest at Candahar. 1881 Times 14 Apr. 5/6 The death is announced of Aga Khan, Chief of the Khojas. 1902 Encycl. Brit. XXV. 163/1 The Aga Khan traced his descent from the royal house of Persia from the most remote, almost prehistoric times. 1951 W. STEVENS Let. 13 Apr. (1967) 716 One is either tripe or the Aga Khan of letters. 1960 H. A. R. GIBB in Encycl. Islam (ed. 2) I. 246 Aa n, properly n..was originally an honorary title at the court of the jr hs of Persia, borne by asan ‘Al h, who..fled in 1840 to Sind. 1970 [see KHOJA 2].