Define De*fine", v. t. [imp. & p. p. Defined; p. pr. & vb. n. Defining.] [OE. definer, usually, to end, to finish, F. d['e]finir to define, L. definire to limit, define; de- + finire to limit, end, finis boundary, limit, end. See Final, Finish.] 1. To fix the bounds of; to bring to a termination; to end. ``To define controversies.'' --Barrow. 2. To determine or clearly exhibit the boundaries of; to mark the limits of; as, to define the extent of a kingdom or country. 3. To determine with precision; to mark out with distinctness; to ascertain or exhibit clearly; as, the defining power of an optical instrument. Rings . . . very distinct and well defined. --Sir I. Newton. 4. To determine the precise signification of; to fix the meaning of; to describe accurately; to explain; to expound or interpret; as, to define a word, a phrase, or a scientific term. They define virtue to be life ordered according to nature. --Robynson (More's Utopia).