Family name เพียรธรรมดี (เพียรธรรมดี 
, Peantamdee, Pienthumdee 
) , all over the world, is a very rare cognomen. The cognomen เพียรธรรมดี is characteristic of Thailand, where it is a very rare surname, and the United States, where it is an extremely rare surname.
| VARIANT | COUNTRY |
|---|---|
| เพียรธรรมดี | Thailand |
| Pienthumdee | United States, Thailand |