If a word conforms to a certain rule, I call it a Special PoS Word™. Use the following examples to find the rule:
|Special PoS Words™||Not Special PoS Word™|
Special PoS Words™, Not Special PoS Word™ ADVICE, ADVERB PRACTICE, PRACTICAL DEVICE, DEMISE LICENCE, LENIENT
Perhaps these are the only such words exist in standard English.
Also, as a bonus, provide a reasonable expansion for PoS.