Invalid1. (a.) Having no force, effect, or efficacy; void; null; as, an invalid contract or agreement.
2. (a.) of no force, weight, or cogency; not valid; weak.
3. (n.) A person who is weak and infirm; one who is disabled for active service; especially, one in chronic ill health.
4. (n.) Not well; feeble; infirm; sickly; as, he had an invalid daughter.
5. (v. t.) To make or render invalid or infirm.
6. (v. t.) To classify or enroll as an invalid.
Thesaurus Entries
Diogenes, Hieronymian, Hieronymite, Timon of Athens, absonant, afflict, ailing, anchoress, anchorite, annulled, apoplectic, arthritic, ascetic, bad, barren, bedridden invalid, black, blank cartridge, bootless, cachectic, case, castrato, cloistered monk, closet cynic, consumptive, contradictory, contrary to reason, counterproductive, criminal, cripple, debilitate, debilitated, derange, desert fathers, desert saints, devitalize, disable, disabled, disorder, drained, dud, dyspeptic, effete, empty, enervate, enervated, enfeeble, epileptic, eremite, erroneous, etiolated, eunuch, evil, exhausted, failing, fallacious, FALSE, fatuitous, fatuous, faulty, feckless, feeble, flawed, frail, fruitless, futile, gelding, healthless, hermit, hermitess, homebody, hospitalize, ill, illogical, impaired, imperfect, impotent, improper, in poor health, inaccurate, inadequate, inane, inauspicious, inauthentic, incapacitate, incompetent, inconclusive, incongruous, inconsequent, inconsequential, inconsistent, incorrect, incurable, indispose, ineffective, ineffectual, inefficacious, inexpedient, inferior, infirm, inoperative, inpatient, irrational, isolationist, languishing, lay up, loner, loose, mad, malevolent, marabout, moribund, nonrational, nonscientific, not following, nugacious, nugatory, null and void, of no force, outcast, outpatient, pale, paralogical, pariah, patient, peaked, peaky, peccant, pillar saint, pillarist, reasonless, recluse, reduce, reduced, reduced in health, repealed, repudiated, revoked, rheumatic, run-down, seclusionist, self-annulling, self-contradictory, self-refuting, senseless, shut-in, sick, sick person, sicken, sickly, sinful, sinister, solitaire, solitary, solitudinarian, sophistic, spastic, spurious, stay-at-home, sterile, stylite, sufferer, terminal case, the sick, unauthentic, unavailing, unconnected, unfavorable, unhealthy, unkind, unphilosophical, unpleasant, unreasonable, unscientific, unskillful, unsound, untenable, untoward, untrue, useless, vain, valetudinarian, valetudinary, vicious, victim, void, weaken, weakened, weakling, weakly, wicked, with low resistance, without reason, wrong