Okay, for a synopsis WITHIN a query, it's a paragraph---possibly two. The entire letter, including address header and signature block, should only be one page. A query synopsis should be very basic. You just want to give them enough of the story that it intrigues them.
Once an agent/editor likes the concept and requests a "synopsis plus a partial manuscript," THEN they're looking for the one to two page synopsis. It's significantly more detailed than a query synopsis, and includes the resolution of all major plot points.
Does that make sense?