That tag is explicitly blacklisted - there's no need to have drupal as part of the tag name, as this is an exclusively Drupal-oriented site.
For reference these are the regular expressions used to prevent those tags from being created:
We couldn't create that tag if we wanted to :)
You can find this discussed in detail here: ...
Since the tag is for the EntityFieldQuery class, I kept entityfieldquery and renamed it entity-field-query to make it clearer. I am now going to put in the tag wiki what was present in the the old wiki tag.
I didn't set any tag synonym, since that is reserved to those cases where editing a question to use the correct tag is not possible (i.e. the wrong tag ...