Legal professionals in the United States increasingly have relied on dictionaries, both current and historical, in court cases. This practice is complicated because originalist jurists are often not well-versed in lexicographical principles that would provide a fuller view of historical reasoning. This Element first contextualizes several issues in early English dictionaries and eighteenth-century language that illustrate how using dictionaries from the Founding Era in questions of law can be problematic: the Element provides examples of words changing over time, explains methodology of devising and borrowing in definitions, details who the readers of such dictionaries were, and more. The Element then excerpts John Mikhail's essential article written in response to the court case CREW vs Trump to show how lexicographical methods and linguistic textual evidence can be better used in legal cases and analysis by triangulating meaning and identifying a prototypical definition.