Synonym for weak ... 1. Wanting physical strength. Specifically: ... Deficient in strength of body; feeble; infirm; sickly; debilitated; enfeebled; exhausted. 'A poor, infirm, weak, and despised old man.' (Shak) 'Weak with hunger, mad with love.' (Dryden) ... Not able to sustain a great weight, pressure, or strain; as, a weak timber; a weak rope. ....