A posimistic person is
someone who has a very positive, affirmative, optimistic, favorable outlook on life.
It's actually a combination of the
words postive and optimistic, hence " posimistic", "posimist " & " posimism ".
The opposite would of-course be "negamistic" , "negamist ", " negamism ", which is a combination of the
words " negative " and " pessimistic " !
"Charlie is always posimistic, expecting
the best in this
best of all possible worlds, but sooner rather than
later he must come to the realization that he cannot have his cake and eat it too !"