Words that contain 'pn' and end in 'na'

Bad news, only 3 entries are availablešŸ˜Ÿ

9 letter words

  • apneumona

10 letter words

  • dipneumona

13 letter words

  • tetrapneumona

How many characters are in the longest word from this list?
The biggest word is 13 letters, which is 'tetrapneumona'.

How many words could one make using the specified combination?
You could assemble 3 words using the specified letter combination.

Is there an example of a word from this page of word that has 'pn' in and ends with 'na' that could be considered as unique?
The most weird word from this list is 'apneumona'. It is defined as "An order of holothurians in which the internal respiratory organs are wanting; -- called also Apoda or Apodes.".