function tooltipContent( $content ) {

		global $id; // This is the Post ID, [@see WP_Query::setup_postdata, ...]

		if ( ! empty( $this->glossaryTerms ) && isset( $this->glossaryTerms[ $id ] ) ) {
			$glossary_terms = $this->glossaryTerms[ $id ];
		} else {
			return $content;
		}

		$content .= '<div class="glossary">';

		foreach ( $glossary_terms as $glossary_term_id => $glossary_term ) {
			$identifier = "$id-$glossary_term_id";
			$content .= '<div class="glossary__tooltip" id="' . $identifier . '" hidden>' . wpautop( $glossary_term ) . '</div>';
		}

		$content .= '</div>';

		return $content;
	}