Webster's Revised Unabridged Dictionary · 1913

Weak

Weak (wēk) , adjective

[Old English weik, Icelandic veikr; akin to Swedish vek, Danish veg soft, flexible, pliant, Anglo-Saxon wāc weak, soft, pliant, Dutch week, German weich, Old High German weih; all from the verb seen in Icelandic vīkja to turn, veer, recede, Anglo-Saxon wīcan to yield, give way, German weichen, Old High German wīhhan, akin to Sanskrit vij, and probably to English week, Latin vicis a change, turn, Greek e'i`kein to yield, give way. r132. Compare Week, Wink, v. i. Vicissitude.]

1.
Wanting physical strength.
(a)
Deficient in strength of body; feeble; infirm; sickly; debilitated; enfeebled; exhausted.
A poor, infirm, weak, and despised old man. — Shakespeare
Weak with hunger, mad with love. — Dryden
(b)
Not able to sustain a great weight, pressure, or strain; as, a weak timber; a weak rope.
(c)
Not firmly united or adhesive; easily broken or separated into pieces; not compact; as, a weak ship.
(d)
Not stiff; pliant; frail; soft; as, the weak stalk of a plant.
(e)
Not able to resist external force or onset; easily subdued or overcome; as, a weak barrier; as, a weak fortress.
(f)
Lacking force of utterance or sound; not sonorous; low; small; feeble; faint.
A voice not soft, weak, piping, and womanish. — Ascham
(g)
Not thoroughly or abundantly impregnated with the usual or required ingredients, or with stimulating and nourishing substances; of less than the usual strength; as, weak tea, broth, or liquor; a weak decoction or solution; a weak dose of medicine.
(h)
Lacking ability for an appropriate function or office; as, weak eyes; a weak stomach; a weak magistrate; a weak regiment, or army.
2.
Not possessing or manifesting intellectual, logical, moral, or political strength, vigor, etc.
(a)
Feeble of mind; wanting discernment; lacking vigor; spiritless; as, a weak king or magistrate.
To think every thing disputable is a proof of a weak mind and captious temper. — Beattie
Origen was never weak enough to imagine that there were two Gods. — Waterland
(b)
Resulting from, or indicating, lack of judgment, discernment, or firmness; unwise; hence, foolish.
If evil thence ensue, She first his weak indulgence will accuse. — Milton
(c)
Not having full confidence or conviction; not decided or confirmed; vacillating; wavering.
Him that is weak in the faith receive ye, but not to doubtful disputations. — Rom. xiv. 1
(d)
Not able to withstand temptation, urgency, persuasion, etc.; easily impressed, moved, or overcome; accessible; vulnerable; as, weak resolutions; weak virtue.
Guard thy heart On this weak side, where most our nature fails. — Addison
(e)
Wanting in power to influence or bind; as, weak ties; a weak sense of honor of duty.
(f)
Not having power to convince; not supported by force of reason or truth; unsustained; as, a weak argument or case.
Convinced of his weak arguing. — Milton
A case so weak... hath much persisted in. — Hooker
(g)
Wanting in point or vigor of expression; as, a weak sentence; a weak style.
(h)
Not prevalent or effective, or not felt to be prevalent; not potent; feeble.
Weak prayers. — Shakespeare
(i)
Lacking in elements of political strength; not wielding or having authority or energy; deficient in the resources that are essential to a ruler or nation; as, a weak monarch; a weak government or state.
I must make fair weather yet awhile, Till Henry be more weak, and I more strong. — Shakespeare
(k)
(Stock Exchange) Tending towards lower prices; as, a weak market.
3.
(a) (Grammar) Pertaining to, or designating, a verb which forms its preterit (imperfect) and past participle by adding to the present the suffix -ed, -d, or the variant form -t; as in the verbs abash, abashed; abate, abated; deny, denied; feel, felt. See Strong, 19 (a).
(b)
(Grammar) Pertaining to, or designating, a noun in Anglo-Saxon, etc., the stem of which ends in -n. See Strong, 19 (b).
4.
(Stock Exchange) Tending toward a lower price or lower prices; as, wheat is weak; a weak market.
5.
(Card Playing) Lacking in good cards; deficient as to number or strength; as, a hand weak in trumps.
6.
(Photography) Lacking contrast; as, a weak negative.

Weak is often used in the formation of self-explaining compounds; as, weak-eyed, weak-handed, weak-hearted, weak-minded, weak-spirited, and the like.

Collocations (4)
Weak conjugation (Grammar) , the conjugation of weak verbs; -- called also new conjugation, or regular conjugation, and distinguished from the old conjugation, or irregular conjugation.
Weak declension (Anglo-Saxon Grammar) , the declension of weak nouns; also, one of the declensions of adjectives.
Weak side , the side or aspect of a person's character or disposition by which he is most easily affected or influenced; weakness; infirmity.
weak sore or weak ulcer (Medicine) , a sore covered with pale, flabby, sluggish granulations.

Weak , verb, transitive and intransitive

[Compare Anglo-Saxon w{not transcribed}can. wācian. See Weak, a.]

To make or become weak; to weaken. [Rare]
Never to seek weaking variety. — Marston