To state the precise meaning of (a word or sense of a word, for example).
To describe the nature or basic qualities of; explain: define the properties of a new drug; a study that defines people according to their median incomes.
To delineate the outline or form of: gentle hills that were defined against the sky.
To specify distinctly: define the weapons to be used in limited warfare.
To give form or meaning to: "For him, a life is defined by action” ( Jay Parini).