If you deactivate plugins you can access them some time under the "Recently active" link in the plugin list table.
"Recently" is not a very specific statement. So how long are deactivated plugins assumed to be "recent"? To find this out we have to take a look at the source code. In
wp-admin/plugins.php line 166 the option "recently_activated" gets updated if a plugin is deactivated:
if ( ! is_network_admin() )
update_option( 'recently_activated', array( $plugin => time() ) +
(array) get_option( 'recently_activated' ) );
The option contains an associative array containing the path to the main file of the plugin as the key and the time the plugins have been deactivated (as a unix timestamp) stored as a serialized value:
Before the plugin table is created the time stamp is used to determine the "recently active" plugins (
wp-admin/includes/class-wp-plugins-list-table.php line 76):
$recently_activated = get_option( 'recently_activated', array() );
foreach ( $recently_activated as $key => $time )
if ( $time + WEEK_IN_SECONDS < time() )
unset( $recently_activated[$key] );
update_option( 'recently_activated', $recently_activated );
The code is walking through all plugin names stored in "recently_activated" and removes those which are older than one week and saves the others back in the options table.
So the answer to the question is: WordPress defines "recently" as one week.