Effendi, Effendy or Efendi (originally from Greek: αφέντης IPA: [aˈfendis]; in Ottoman Turkish language: افندي Efendi, in Arabic: أفندي, Afandī; in Persian: آفندی) is a title of nobility meaning a Lord or Master.
It is a title of respect or courtesy, equivalent to the English Sir, which was used in the Ottoman Empire and Byzantine Empire. It follows the personal name, when it is used, and is generally given to members of the learned professions and to government officials who have high ranks, such as bey or pasha. It may also indicate a definite office, as hekim efendi, chief physician to the sultan. The possessive form efendim (my master) is used by servants, in formal discourse, when answering the telephone, and can substitute for "excuse me" in some situations (e.g. asking someone to repeat something) .
In the Ottoman era, the most common title affixed to a personal name after that of agha was efendi. Such a title would have indicated an "educated gentleman", hence by implication a graduate of a secular state school (rüşdiye), even though at least some if not most of these efendis had once been religious students, or even religious teachers.
The Ottoman Turkish word افندي efendi, in modern Turkish efendi, is a borrowing of the Medieval Greek ἀφέντης afendēs, from Ancient Greek αὐθέντης authentēs, "master, author, doer, perpetrator" (cf. ). This word was widely used as a title for Byzantine nobles as late as 1465, such as in the letters of Cardinal Bessarion concerning the children of Thomas Paleologus.