Unrealistic means not based on reality or being false, untrue or misleading. It refers to something that is not grounded in fact or does not correspond with actuality and can be seen as overly idealized, exaggerated or impractical.
Usage examples
The budget proposed by the client for the project was unrealistic as it did not account for the necessary resources and time required.
The movie's plot was deemed unrealistic by critics due to its lack of logical development and overly exaggerated scenes.
The sales targets set by the management were considered unrealistic by the sales team, as they were significantly higher than previous years' performances.
The student's expectation of completing a complex engineering project within a week was unrealistic, given the amount of research and planning required.
The athlete's ambition to break a world record without any prior training or experience in the sport was unrealistic and led to disappointment.
This includes our relationships and I think we have an epidemic of unhappy people who are unhappy because of unrealistic expectations of how life should be. (omgchronicles.vickilarson.com)
This is science fiction with giant fighting robots, and it was completely unrealistic in more moments than not. (awardscircuit.com)
The worst case scenario is that you ignore rebalancing completely, so don't set unrealistic goals that you can't commit to. (monevator.com)