skeptimistic
adj. Simultaneously skeptical and optimistic.
skeptimist n.
skeptimism n.

Example Citations:
Well, if we collectively understood the imminent danger to our way of life, we might change. But history is full of examples that show people don't change until disaster strikes. So who knows. Perhaps in this era of information and knowledge, we just might find the wisdom to shape a different historical outcome. Until then, I remain cautiously skeptimistic.
—Everette Surgenor, "Cautiously skeptimistic: Can we revamp Canadian education?," The Globe and Mail, December 28, 2010

Sen. John Lee, D-North Las Vegas, said he was "skeptimistic," both optimistic and skeptical, of any government plan that could bring back the construction industry.
—Ray Hagar, "Lawmakers hear about plight of unemployed construction workers," Reno Gazette-Journal, February 10, 2011

Earliest Citation:
Mark Twain is classically American. He's energetic, skeptimistic (a word my wife invented), adventurous and boldly outspoken.
—"This is the Picture," The Reluctant Blogger, July 14, 2005

Notes:
Urban Dictionary has a couple of earlier citations, one of which is defined oddly ("Unsure about a particular situation") and the other is just silly ("A state of being skeptical and pessimistic about anything relating to llamas or your mom").

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