This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

Of or pertaining to meliorism: correlated with optimistic and pessimistic.

"He is but a hubristic neophyte, a man clinging with fervor to long-discredited melioristic chimera and a man who is followed by throngs of frothy-mouthed, purblind acolytes, wishing to foment change yet knowing not even for what they cheer; to brand them Pollyannas is to demean and debase a harmless member of our lexicon."

hopeful