The definition of wit that is used in the 21st century is lacking, because it does not consider the richness of meaning inherent in definitions from Renaissance English. This thesis provides an in-depth presentation of the varied meanings of wit, and an exploration of theories surrounding the brain and body in the Renaissance. Overall, the thesis shows that the range of wit is extensive, stretching from a bodily sense to an apt expression. In order to illustrate more fully the ways in which wit functions within poetry, this work examines John Donne, a poet from the Renaissance noted for his wit. Donne uses both conventional definitions of wit and invents new meanings, which enrich the definition of wit in his time period.