valid

Synonyms

analytic (or analytical), coherent, consequent, good, logical, rational, reasonable, sensible, sound, well-founded, well-grounded;

Antonyms

illegitimate, illogical, incoherent, inconsequent, inconsequential, invalid, irrational, unreasonable, unsound, weak;

Near Antonyms

fallacious, misleading, sophistic (or sophistical), specious;

unarticulated;

unscientific;

absurd, cockeyed, crazy, daffy, fatuous, half-baked, half-witted, harebrained, insane, loony (also looney), mad, nonsensical, nutty, preposterous, simpleminded, stupid, weak-minded, witless;

senseless, thoughtless;

uncompelling, unconvincing;

Related Words

cognitive, empirical (also empiric);

defendable, defensible, justifiable, maintainable, supportable, sustainable, tenable;