If you describe someone as impractical, you mean that they do not have the abilities or skills to do practical work such as making, repairing, or organizing things. Geniuses are supposed to be difficult, eccentric and hopelessly impractical.

Is there such a word as impractical?

not practical or useful. not capable of dealing with practical matters; lacking sense.

Is it impractical or impracticable?

Basically, Impracticable is something that cannot be practiced with what you have at your command, while Impractical is something that is unwise to practice.