Overlord \O"ver*lord`\, n. One who is lord over another or others; a superior lord; a master. --Freeman. [1913 Webster]

Source: The Collaborative International Dictionary of English v.0.48
 

51 Moby Thesaurus words for "overlord": anointed king, boss, bwana, chef, chief, chieftain, church dignitary, crowned head, dynast, ecclesiarch, elder, emperor, employer, goodman, grand duke, guru, high chief, husband, imperator, king, king-emperor, kinglet, liege, liege lord, lord, lord paramount, majesty, master, monarch, padrone, paramount, paterfamilias, patriarch, patron, petty king, potentate, prince, prince consort, rabbi, royal, royal personage, royalty, ruler, sahib, seigneur, seignior, sovereign, starets, suzerain, teacher, tetrarch

Source: Moby Thesaurus II by Grady Ward, 1.0
 

overlord

Source: WordNet (r) 2.0
 

Overlord \O"ver*lord`\, n. One who is lord over another or others; a superior lord; a master. --Freeman.

Source: Webster's Revised Unabridged Dictionary (1913)