an implied line is one that

These two sites will give you both illustrations and definition.

http://www.artsconnected.org/toolkit/encyc_lineimplied.html

http://drawsketch.about.com/od/drawinglessonsandtips/ss/contourdrawing_2.htm

An implied line is one that is not physically present or drawn, but is suggested or created by the arrangement of objects, shapes, or elements within a composition. It is a line that is implied or suggested by the direction or movement of other elements in the artwork.

To understand and identify an implied line, you can follow these steps:

1. Observe the composition: Look at the overall arrangement of shapes, objects, or elements within the artwork.
2. Look for directional cues: Identify any elements or objects that appear to be pointing or leading the viewer's eye in a specific direction.
3. Consider the relationships between elements: Analyze how different elements in the artwork relate to each other and create a sense of visual connection.
4. Identify areas of continuity: Notice if there is a continuous flow or relationship between different elements, even if there is no actual line connecting them.
5. Interpret the visual movement: Based on the observations, identify any implied lines that are suggested by the arrangement and movement of the elements.

By following these steps and analyzing the visual elements, you will be able to identify and understand the concept of an implied line in an artwork.