infirm

UK: /ɪnˈfɜː^rm/ US: /ɪnˈfɝm/ ,(in fûrm′)

WordReference Random House Learner's Dictionary of American English © 2025

in•firm /ɪnˈfɜrm/   adj. 

1. feeble or weak because of age:
   The old man was too infirm to walk.

n. the infirm, [plural* used with a plural verb]

2. infirm people:
   care of the infirm.

WordReference Random House Unabridged Dictionary of American English © 2025

in•firm  (in fûrm′), adj. 

1. feeble or weak in body or health, esp. because of age;
   ailing.
2. unsteadfast, faltering, or irresolute, as persons or the mind;
   vacillating:
   infirm of purpose.
3. not firm, solid, or strong:
   an infirm support.
4. unsound or invalid, as an argument or a property title.

v.t. 

5. to invalidate.

• Latin infirmus. See in-³, firm¹
• Middle English infirme 1325–75

in•firm′ly, adv. 
in•firm′ness, n. 
Synonyms

• 1, 3.
• 4. weak.
• 2. wavering, indecisive.
• 3. rickety, tottering, shaky, unsteady.

Antonyms

• 1, 2.
• 3. strong.

Collins Concise English Dictionary © HarperCollins Publishers::

infirm / ɪnˈfɜːm/ adjective

1. weak in health or body, esp from old age
2. (as collective noun; preceded by the): the infirm
3. lacking moral certainty; indecisive or irresolute
4. not stable, sound, or secure: an infirm structure
5. (of a law, custom, etc) lacking legal force; invalid: an infirm claim

inˈfirmly adverb

inˈfirmness noun