out·line / ˈoutˌlīn/ • n. 1. a line or set of lines enclosing or indicating the shape of an object in a sketch or diagram: fill in the outlines with color. ∎ a line or set of lines of this type, perceived as defining the contours or bounds of an object: the outlines of her face.2. a general plan giving the essential features but not the detail: an outline of the theory of evolution a course outline. ∎ a draft of a diagram, plan, proposal, etc., summarizing the main points: draw up an outline for the essay. ∎ the main features or general principles of something: the main outlines of Elizabeth's career.• v. [tr.] 1. draw, trace, or define the outer edge or shape of (something): her large eyes were darkly outlined with eyeliner.2. give a summary of (something): she outlined the case briefly.