I get the sense that the concept of "Turkish" changed from culture to culture, and maybe lacked a certain coherence or concreteness.
Who considered themselves Turkish? Did they hold multiple identities, and, if so, how important was the Turkish component to this identity?
Did the Ottomans consider themselves or the people they ruled to be Turkish? If no, how did they conceive of themselves and the peoples they ruled?
Did Iranians make a meaningful distinction between Turkish and Mongol? I read some of the works of Ubayd Zakani, and Turks often feature in anecdotes that involve murder and rape. Were Turks widely seen as violent?
Who did Europeans consider Turkish? Did eastern and western Europeans conceptions of Turkishness agree?
As an exonym, Early Modern Europeans often used the word "Turk" to describe any Levantine or Balkan Muslims, regardless of their looks or geographical origin. In the context of the time, it was more of a religious and political identity than an ethnic or linguistic identity that it is today. Essentially, "Turk" was a slang or shorthand for "Moslem from an Ottoman-controlled area".