When it comes to synonyms of "quiddity," the Q's have it. Consider "quintessence," a synonym of the "essence of a thing" sense of "quiddity" (this oldest sense of "quiddity" dates from the 14th century). "Quibble" is a synonym of the "trifling point" sense; that meaning of "quiddity" arose from the subtler points of 16th-century academic arguments. And "quirk," like "quiddity," can refer to a person's eccentricities. Of course, "quiddity" also derives from a "Q" word, the Latin pronoun "quis," which is one of two Latin words for "who" (the other is "qui"). "Quid," the neuter form of "quis," gave rise to the Medieval Latin "quidditas," which means "essence," a term that was essential to the development of the English "quiddity."