Impractical (adjective)

1. Not practical or sensible; not likely to be successful or useful in practice.
2. Not suited to actual use or to real-life conditions.
3. Not able to be put into practice; not possible to do.

Origin:

From the latin word "impracticus" meaning "not practical".

Examples:

1. The idea of living on the moon was seen as impractical.
2. The plan was too impractical to be implemented.
3. The solution was impractical and would have required too many resources.
4. The design was beautiful but impractical for everyday use.
5. The idea was deemed impractical due to lack of funding.