1. (a.) Not possible; incapable of being done, of existing, etc.; unattainable in the nature of things, or by means at command; insuperably difficult under the circumstances; absurd or impracticable; not feasible.

2. (n.) An impossibility.

I refuse I will not absurd algorismic algorithmic aliquot antic barred by no means cardinal closed-out contrary to reason count me out crazy cureless decimal differential digital even exceptionable excluded exponential fanciful fantastic farcical figural figurate figurative finite fractional hopeless illogical imaginary immedicable impair impracticable impractical inadmissible include me out incomprehensible inconceivable incredible incurable indefensible infeasible infinite integral intolerable irrational irremediable irreparable logarithmic logically impossible logometric ludicrous negative no no go not likely not possible nothing doing numeral numerary numerative numeric objectionable odd ordinal outlandish outrageous oxymoronic pair paradoxical positive possible preposterous prime prohibited radical rational real reciprocal ridiculous ruled-out self-contradictory submultiple surd transcendental unacceptable unaccountable unachievable unattainable unbelievable uncorrectable undesirable unexpected unfeasible unimaginable unobtainable unrealizable unreasonable unsolvable unsuitable untenable unthinkable unworkable weird