The quality or state of being free from phlegm or having had phlegm removed.
From dephlegmed (adjective) + -ness (forming abstract nouns). An extremely rare noun form from medieval/early modern chemistry terminology.
This word is so obscure it almost certainly appears in fewer than five printed books—it's a perfect example of how old scientific languages created words that nobody would ever actually need to use.
Complete word intelligence in one call. Free tier — 50 lookups/day.