de·fine 
(dĭ-fīn)
(dĭ-fīn)v. de·fined, de·fin·ing, de·fines
v.tr.
1.
a. To state the precise meaning of (a word or sense of a word, for example).
b. 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.
2.
a. To make clear the outline or form of; delineate: gentle hills that were defined against the sky.
b. To specify distinctly: define the weapons to be used in limited warfare.
3. To give form or meaning to: "For him, a life is defined by action" (Jay Parini).
v.intr.
To make or write a definition.
[Middle English definen, diffinen, from Old French definir, diffiner, from Latin dēfīnīre, to limit, determine : dē-, intensive pref.; see DE- + fīnis, boundary, limit.]
de·fin′a·bili·ty n.
de·fina·ble adj.
de·fina·bly adv.
de·finement n.
de·finer n.