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"
incapable of failure or error; "an infallible antidote"; "an infallible memory"; "the Catholic Church considers the Pope infallible"; "no doctor is infallible"
being or characterized by concepts or their formation; "conceptual discussions"; "the schizophrenic loses ability to abstract or do conceptual thinking"; "sex is a notional category, gender is a grammatical category"