Wikipedia does not currently have an article on "plumpness", but our sister project Wiktionary does:

Read the Wiktionary entry on "plumpness"

You can also:

• Search for Plumpness in Wikipedia to check for alternative titles or spellings.
• Start the Plumpness article, using the Article Wizard if you wish, or add a request for it; but please remember that Wikipedia is not a dictionary.
  wiktionary:Special:Search/plumpness