Unrealistic means expecting more than could possibly happen. Unrealistic expectations, an unrealistic deadline, wildly unrealistic.
It is the standard criticism of plans and of deadlines, and it is about the world rather than the person: an unrealistic deadline is one nobody could meet. Unrealistic expectations is the fixed phrase in psychology.
1adjectiveunrealisticExpecting more than could possibly happen.
“It's unrealistic to expect to become fluent in a language in a month.”
unrealistic is a quality.
From un- + realistic.
Etymology from Wiktionary, CC BY-SA