In Scottish poetry and literature, ilk functions in two primary ways. As an adjective (often in the form ilka), it means "each" or "every" and appears frequently in traditional and literary Scots verse. As a noun, its most distinctive Scottish usage is in the phrase of that ilk, which historically indicated that a person's surname matched the name of their landed estate—for example, "Grant of that ilk" meant Grant of Grant. This usage arose from the Scottish practice of landowners taking their surnames from their estates. A later, erroneous interpretation of this phrase led to the modern English sense of ilk meaning "type" or "sort".

Etymology: The adjectival sense derives from Old English ælc (each), via Middle English northern variants. The of that ilk construction is uniquely Scottish in origin. Related forms: Ilka is the more common form for "each, every" in modern Scots, while ilk in this sense is now mainly literary. Common pitfall: Modern English speakers often use ilk to mean "type" or "kind" (e.g., "politicians of that ilk"), but this usage arose from a misunderstanding of the Scottish phrase of that ilk. Some traditionalists consider the modern usage incorrect. Historical note: The phrase of that ilk was used to distinguish the senior branch of a landed family from cadet branches—for instance, "Houstoun of that ilk" meant Houstoun of Houstoun. Cross-reference: Related to the Scots term ilka (each, every).