WordPress at a glance
action is not described

pre_delete_term action-hook . WP 4.1.0

Fires when deleting a term, before any modifications are made to posts or terms.

Usage

add_action( 'pre_delete_term', 'action_function_name_3578', 10, 2 );
function action_function_name_3578( $term, $taxonomy ){
	// action...
}
$term(int)
Term ID.
$taxonomy(string)
Taxonomy Name.

Where the hook is called

wp_delete_term()
wp-includes/taxonomy.php 1704
do_action( 'pre_delete_term', $term, $taxonomy );

Where the hook is used (in WP core)

Does not used.