1) Airy 2) Armchair 3) Blue sky 4) Harebrained 5) Impossible 6) Meshuga 7) Meshugga 8) Meshugge 9) Meshuggeneh 10) Meshuggener 11) Naive 12) Quixotic 13) Screwball 14) Softheaded 15) Stupid 16) Unfunctional 17) Unpractical 18) Unrealistic 19) Visionary 1) Armchair 2) Crazy 3) Half-baked 4) Idealistic 5) Impossible 6) Impracticable 7) Improbable 8) Lacking sense 9) Meshuga 10) Meshugga 11) Meshugge 12) Meshuggeneh 13) Meshuggener 14) Naive 15) Not practical 16) Not practical or realizable 17) Not practical or useful 18) Not suitable for use 19) Not viable 
• (a.) Not practical.
Im·prac'ti·cal adjective Not practical. 
[adj] - not practical
adjective 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`; `an impractical solution`
not practical or useful. · not capable of dealing with practical matters; lacking sense. · idealistic. · impracticable.