content, excerpt…and summary/description?

Before I jump into what I’m wanting to do, I want to have the following definitions clear;

An excerpt = The first however many chars of the post = the_excerpt();

The content = The entire content = the_content();

Summary/description = a summary/description of the post, written by the user.

I know I can have the excerpt serve a summary’s purpose but I don’t want to do that because I’m using excerpts for my archive pages.

I want post descriptions to appear in search results, I know how to have the excerpt work there but I was wondering if there was a third function that would help me out with this?

If there isn’t one, is there a plugin available, or directions in writing a function similar to the excerpt?

I have some programming experince so jumping in the code isn’t going to drive me away, I’m open to any suggestions.