Optimistic

google

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mid 18th century: from French optimisme, from Latin optimum ‘best thing’ (see optimum).

wiktionary

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optimist +‎  -ic

etymonline

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optimistic (adj.)

"of, pertaining to, or characterized by optimism; disposed to take the most hopeful view of a matter," 1845, from optimist + -ic. Related: Optimistical (1809); optimistically.