In Drupal 6, you can get the term object using the following function

taxonomy_get_term($tid);

 

In Druapl 7, this function is deprecated but you can get the term by term name.

taxonomy_get_term_by_name($name);

If you want to get the term by term ID, there is not yet a official solution but hopefully you could find more information in the following discussions.

• taxonomy_node_get_terms() in Drupal 7
• taxonomy_node_get_terms doesn’t work with drupal 7

Done =)

Reference:

• Drupal 6 API – taxonomy_get_term
• Drupal 7 API – taxonomy_get_term_by_name