The more directive is supplied by the more plugin.

This directive provides a way to have a "more" link on a post in a blog, that leads to the full version of the page. Use it like this:

[[!more  linktext="click for more" text="""
This is the rest of my post. Not intended for people catching up on
their blogs at 30,000 feet. Because I like to make things
difficult.
"""]]

If the linktext parameter is omitted it defaults to just "more".

An optional pages parameter can be used to specify a PageSpec, and then the "more" link will only be displayed when the page is inlined into a page matching that PageSpec, and otherwise the full content shown.

Note that you can accomplish something similar using a toggle instead.