See infirm in Webster's New World Roget's A-Z Thesaurus II
adjective
Not physically strong:
decrepit, delicate, feeble, flimsy, fragile, frail, insubstantial, puny, unsound, unsubstantial, weak, weakly. See strongLacking stability:
insecure, precarious, shaky, tottering, tottery, unstable, unsteady, unsure, weak, wobbly. See change, strong
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