Real Dictionary

outline
An outline is a general explanation or description of something.
countable noun: The outline of something is its general shape, especially when it cannot be clearly seen.
passive verb: You say that an object is outlined when you can see its general shape because there is light behind it.
verb: If you outline an idea or a plan, you explain it in a general way.

outline in American English
a line bounding the limits of an object, showing its shape; contour line
to draw a profile of; draw in outline
noun: the line by which a figure or object is defined or bounded; contour
transitive verb: to draw the outline of, or draw in outline, as a figure or object

outline in British English
to draw or display the outline of
noun: a preliminary or schematic plan, draft, account, etc
noun: an outline; summary