- feeble or weak in body or health, especially because of age; ailing.
- unsteadfast, faltering, or irresolute, as persons or the mind; vacillating: infirm of purpose.
- not firm, solid, or strong: an infirm support.
- unsound or invalid, as an argument or a property title.
- to invalidate.
Origin of infirm
SynonymsSee more synonyms on Thesaurus.com
- weak in health or body, esp from old age
- (as collective noun; preceded by the)the infirm
- lacking moral certainty; indecisive or irresolute
- not stable, sound, or securean infirm structure; an infirm claim
- law (of a law, custom, etc) lacking legal force; invalid
Word Origin and History for infirming
late 14c., "weak, unsound" (of things), from Latin infirmus "weak, frail, feeble" (figuratively "superstitious, pusillanimous, inconstant"), from in- "not, opposite of" (see in- (1)) + firmus (see firm (adj.)). Of persons, "not strong, unhealthy," first recorded c.1600. As a noun from 1711.
- Weak in body, especially from old age or disease; feeble.