gist

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The central idea; the essence. synonym: substance.
• noun Law The grounds for action in a suit.

from The Century Dictionary.

• noun The point on which an action rests; the substance or pith of a matter; the main point: as, the gist of an argument.
• noun A resting-place; a couch.
• noun A lodging-place; a place of rest or halt in traveling.
• noun A beam: same as joist.
• An aphetic form of agist (which see).

from the GNU version of the Collaborative International Dictionary of English.

• noun obsolete A resting place.
• noun The main point, as of a question; the point on which an action rests; the pith of a matter.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The most essential part; the main idea or substance (of a longer or more complicated matter).
• noun law, dated The essential ground for action in a suit, without which there is no cause of action.
• noun obsolete Resting place (especially of animals), lodging.
• verb To summarize, to extract and present the most important parts of.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the choicest or most essential or most vital part of some idea or experience
• noun the central meaning or theme of a speech or literary work