How to have contextual filters in views accept words instead of ID numbers?

I'm using Drupal 7, and what I want is to have my views use a contextual filter, so that if a view is located at mydrupalsite.com/myview I want to be able to go to mydrupalsite.com/myview/topicname and have the view use the topicname to filter the content. Topicname in this case is a taxonomy item.

I've followed some tutorials and looked at articles about how to create contextual filters. But the problem I have is that right now the contextual filter does not pick up the topicname in the URL. The filter does work if I provide the ID number of the taxonomy item, so mydrupalsite.com/myview/93 will work (if 93 is the ID number of the taxonomy item).

How can I get the view to work so that the contextual filter reads the topicname?

Thanks