invalid
1 of 4adjective (1)
in·val·id (ˌ)in-ˈva-ləd 
: not valid:
a
: being without foundation or force in fact, truth, or law
an invalid assumption
declared the will invalid
b
: logically inconsequent
invalidly
(ˌ)in-ˈva-ləd-lē
adverb invalid
2 of 4noun
in·va·lid ˈin-və-ləd
British usually -ˌlēd
: one who is sickly or disabled
invalid
3 of 4verb
in·va·lid ˈin-və-ləd
-ˌlid,
British usually -ˌlēd,
or ˌin-və-ˈlēd
invalided; invaliding; invalids
transitive verb
1
: to remove from active duty by reason of sickness or disability
2
: to make sickly or disabled
invalid
4 of 4adjective (2)
in·va·lid ˈin-və-ləd
British usually -ˌlēd
1
: affected by disease or disability : sickly
2
: of, relating to, or suited to one that is sick
an invalid chair
Synonyms
Adjective (1)
- bad
- inoperative
- nonbinding
- nonvalid
- nugatory
- null
- null and void
- void
Adjective (2)
- ailing
- sickly
- weakly
See all Synonyms & Antonyms 
Example Sentences
Noun Her husband has become an invalid.
Word History
Etymology
Adjective (1)
Latin invalidus weak, from in- + validus strong — more at valid
Adjective (2)
Latin & French; French invalide, from Latin invalidus
First Known Use
Adjective (1)
1542, in the meaning defined above
Noun
1701, in the meaning defined above
Verb
1787, in the meaning defined at sense 1
Adjective (2)
1642, in the meaning defined at sense 1
Kids Definition
invalid 1 of 2
adjective
in·val·id in-ˈva-ləd
: having no force or effect
invalid
2 of 2noun
in·va·lid ˈin-və-ləd
: a person suffering from sickness or disability
Medical Definition
invalid 1 of 3
adjective
in·va·lid
ˈin-və-ləd, British usually -ˌlēd
1
: affected by disease or disability : sickly
2
: of, relating to, or suited to one that is sick
an invalid chair
invalid
2 of 3noun
: one who is sickly or disabled
invalid
3 of 3transitive verb
in·va·lid
ˈin-və-ləd, -ˌlid, British usually -ˌlēd or ˌin-və-ˈlēd
1
: to remove from active duty by reason of sickness or disability
was invalided out of the army
2
: to make sickly or disabled
a patient invalided by valvular disease
Legal Definition
invalid
adjective
in·val·id in-ˈva-ləd
: being without force or effect under the law
declared the will invalid
invalid 1 of 3
adjective (1)
as in weak
chronically or repeatedly suffering from poor health an old and now invalid woman who rarely gets out anymore Synonyms & Similar Words
Relevance
- weak
- fragile
- weakly
- sickly
- dying
- sick
- frail
- ailing
- feeble
- lame
- weakened
- challenged
- fading
- incurable
- incapacitated
- bedridden
- enfeebled
- unsound
- unhealthy
- decrepit
- debilitated
- moribund
- poorly
- infirm
- delicate
- ill
- bedfast
- unwell
- worn-out
- indisposed
- peaked
- run-down
Antonyms & Near Antonyms
- healthy
- well
- whole
- wholesome
- sound
- fit
- hale
- able-bodied
- hearty
- well-conditioned
invalid
2 of 3adjective (2)
1
as in null
having no legal or binding force the treaty is invalid once one side violates it Synonyms & Similar Words
- null
- void
- illegal
- inoperative
- worthless
- nugatory
- useless
- null and void
- nonvalid
- bad
- nonbinding
- ineffective
- ineffectual
Antonyms & Near Antonyms
- valid
- good
- legal
- binding
- working
2
as in erroneous
not being in agreement with what is true that's an invalid assumption on your part Synonyms & Similar Words
- erroneous
- incorrect
- inaccurate
- wrong
- false
- misleading
- untrue
- inexact
- unsound
- distorted
- untruthful
- off base
- fraudulent
- spurious
- off
- specious
- deceptive
- fallacious
- fictitious
- illusory
- delusive
- delusory
- dishonest
- askew
- counterfactual
- unproven
- untested
- deceitful
- unconfirmed
- lying
- mendacious
- awry
- invented
- amiss
- fabricated
- made-up
- trumped-up
Antonyms & Near Antonyms
- valid
- correct
- true
- accurate
- proper
- right
- exact
- sound
- precise
- factual
- confirmed
- demonstrated
- tested
- proven
- established
- errorless
- perfect
- veracious
- faultless
- flawless
- impeccable
- letter-perfect
3
as in unreasonable
not using or following good reasoning an argument which has one untrue premise is invalid Synonyms & Similar Words
- unreasonable
- illegitimate
- irrational
- unreasoning
- misleading
- weak
- illogical
- absurd
- unreasoned
- fallacious
- silly
- foolish
- inconsequent
- inconsistent
- unsound
- inconsequential
- meaningless
- weird
- nonrational
- specious
- odd
- unusual
- misguided
- strange
- unconsidered
- insane
- random
- nonsensical
- unconvincing
- asinine
- sophistic
- eristic
- eristical
- sophistical
- inexplicable
- disorganized
- preposterous
- mad
- ill-advised
- disordered
- surreal
- half-baked
- unaccountable
- whacky
- wacky
- senseless
- unexplainable
- reasonless
- peculiar
- nutty
- rambling
- Kafkaesque
Antonyms & Near Antonyms
- valid
- reasonable
- logical
- sound
- rational
- wise
- sensible
- sane
- justified
- commonsense
- informed
- enlightened
- reasoned
- sober
- just
- well-founded
- plausible
- certain
- clear
- true
- convincing
- persuasive
- solid
- compelling
- well-grounded
- organized
- credible
- ordered
- satisfying
- sure
- cogent
- confirmed
- validated
- demonstrated
- established
- substantiated
- corroborated
4
as in unsupported
having no basis in reason or fact an invalid claim that can be easily disproved by the facts Synonyms & Similar Words
- unreasonable
- unsupported
- unfounded
- baseless
- unwarranted
- false
- unsubstantiated
- irrational
- unnecessary
- groundless
- unreasoned
- absurd
- misleading
- inconsistent
- nonvalid
- illogical
- weak
- wrong
- misled
- fallacious
- meaningless
- untenable
- unconvincing
- implausible
- unsound
- unconscionable
- stupid
- specious
- foundationless
- flimsy
- gratuitous
- silly
- nonlogical
- foolish
- unwise
- nonsensical
- insane
- fatuous
- asinine
- mad
- ill-advised
- preposterous
- lunatic
- simpleminded
- whacky
- uncalled-for
- wacky
- crackpot
- senseless
- harebrained
- nutty
- crazy
- brainless
- half-witted
Antonyms & Near Antonyms
- valid
- reasonable
- good
- justified
- hard
- validated
- reasoned
- certified
- confirmed
- just
- logical
- substantiated
- true
- rational
- informed
- actual
- well-founded
- wise
- real
- verified
- certain
- sensible
- sane
- well-grounded
- genuine
- corroborated
- sure
- commonsense
- sober
- clear
- plausible
- solid
- convincing
- compelling
- persuasive
- sound
- satisfying
- credible
- cogent
invalid
3 of 3verb
as in to damage
Synonyms & Similar Words
- damage
- hurt
- harm
- impair
- exhaust
- disable
- wash out
- lay up
- wear down
- deplete
- injure
- wear out
- cripple
- impoverish
- unman
- grind (down)
- devitalize
- depress
- break down
- weaken
- hamstring
- incapacitate
- waste
- enfeeble
- debilitate
- paralyze
- sap
- tire
- enervate
- etiolate
- soften
- prostrate
Antonyms & Near Antonyms
- strengthen
- fortify
- beef (up)
- energize
- recruit
- rejuvenate
- invigorate
- season
- harden
- vitalize
- toughen