The expressions “of that ilk” and “of his ilk” refer to “type” or “sort,” which is the product of a misunderstanding in translation from the original language. The expression “of that ilk” originated in Scotland, but the Scots language phrase referred to someone “of the same name and place” (for example, “Sir Iain Moncreiffe of that Ilk”). Some traditionalist etymologists feel, therefore, that English speakers shouldn’t use “of that ilk” to refer to similarities in kind and type, because the original referred specifically to names and places of origin. Nonetheless, using “of that ilk” to refer to sorts of people or things is the only way the phrase is commonly used today. While it is in the modern lexicon, it’s an extremely old word, tracing back to the Old English “ilca,” meaning “same,” and the Proto-Germanic “ilīkaz,” also meaning “same.”