The Etymology of Define
Defining a word is, at its etymological core, an act of fencing. Latin dēfīnīre meant 'to set bounds to' — dē- intensifying fīnīre, 'to limit,' from fīnis, 'boundary.' Roman surveyors defined land by marking where one property ended and another began. Philosophers borrowed the spatial metaphor: to define a concept was to draw a line around its meaning, separating it from everything it was not. Aristotle's method of definition by genus and differentia — placing something in a category and then distinguishing it — is essentially this boundary-drawing made systematic. English inherited the word through Old French in the fourteenth century, and both the physical and intellectual senses took hold. A mountain ridge defines a horizon; a dictionary defines a word. The family of fīnis words in English is remarkably large: finite, finish, final, confine, refine, and even finance (originally meaning 'settlement' or 'ending' of a debt). All share the idea that clarity comes from knowing where limits lie.