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 eccentric and hopelessly impractical. practical
not practical or realizable; speculative; "airy theories about socioeconomic improvement"; "visionary schemes for getting rich"
not practical; not workable or not given to practical matters; "refloating the ship proved impractical because of the expense"; "he is intelligent but too impractical for commercial work"
If you describe an object, idea, or course of action as impractical, you mean that it is not sensible or realistic, and does not work well in practice. It became impractical to make a business trip by ocean liner. practical