WordPress at a glance
function is not described

wp_get_split_term() WP 4.2.0

Get the new term ID corresponding to a previously split term.

No Hooks.

Return

Int/false. If a previously split term is found corresponding to the old term_id and taxonomy, the new term_id will be returned. If no previously split term is found matching the parameters, returns false.

Usage

wp_get_split_term( $old_term_id, $taxonomy );
$old_term_id(int) (required)
Term ID. This is the old, pre-split term ID.
$taxonomy(string) (required)
Taxonomy that the term belongs to.

Code of wp get split term: wp-includes/taxonomy.php WP 5.2.2

<?php
function wp_get_split_term( $old_term_id, $taxonomy ) {
	$split_terms = wp_get_split_terms( $old_term_id );

	$term_id = false;
	if ( isset( $split_terms[ $taxonomy ] ) ) {
		$term_id = (int) $split_terms[ $taxonomy ];
	}

	return $term_id;
}