adj. 25B6; adjective
they are too weak to move : FRAIL, feeble, delicate, fragile; infirm, sick, sickly, debilitated, incapacitated, ailing, indisposed, decrepit; tired, fatigued, exhausted; informal weedy.
bats have weak eyes : INADEQUATE, poor, feeble; defective, faulty, deficient, imperfect, substandard.
a weak excuse : UNCONVINCING, untenable, tenuous, implausible, unsatisfactory, poor, inadequate, feeble, flimsy, lame, hollow; informal pathetic.
I was too weak to be a rebel : SPINELESS, craven, cowardly, pusillanimous, timid; irresolute, indecisive, ineffectual, inept, effete, meek, tame, ineffective, impotent, soft, faint-hearted; informal yellow, weak-kneed, gutless, chicken.
a weak light : DIM, pale, wan, faint, feeble, muted.
a weak voice : INDISTINCT, muffled, muted, hushed, faint, low.
weak coffee : WATERY, diluted, dilute, watered down, thin, tasteless, flavourless, bland, insipid, wishy-washy.
a weak smile : UNENTHUSIASTIC, feeble, half-hearted, lame.
strong, powerful, convincing, resolute, bright, loud.