Insert this into your functions.php
add_action('woocommerce_after_single_product_summary', 'urlundcom_add_term_descriptions_to_single_product', 10);
function urlundcom_add_term_descriptions_to_single_product() {
global $product;
$terms = get_the_terms($product->get_id(), 'product_cat');
if (empty($terms)) {
return;
}
$descriptions = [];
foreach ($terms as $term) {
if ($term->description !== '') {
$descriptions[] = $term->description;
}
}
printf('<ul class="term-descriptions"><li>%s</li></ul>', implode('</li><li>', $descriptions));
}