function so_42345940_backorder_message( $text, $product ){ if ( $product->managing_stock() && $product->is_on_backorder( 1 ) ) { $text = __( 'Avaliable on Pre-Order', 'your-textdomain' ); } return $text; } add_filter( 'woocommerce_get_availability_text', 'so_42345940_backorder_message', 10, 2 );