This is from the codex.
<?php get_term_by( $field, $value, $taxonomy, $output, $filter ) ?>
Suppose I have a taxonomy system as follows;
taxonomy: "healthy foods" and it's a hierarchical taxonomy and your hierarchy goes exactly like this;
healthy foods
fruits
red ones
green ones
veggies
red ones
green ones
and you use the get_term_by
function as follows;
get_term_by("name","red ones","healthy foods")
Do you get the veggies or the fruits?