weak

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Lacking physical strength, energy, or vigor; feeble.
2. adj. Likely to fail under pressure, stress, or strain; lacking resistance: a weak link in a chain.
3. adj. Lacking firmness of character or strength of will.
4. adj. Lacking the proper strength or amount of ingredients: weak coffee.
5. adj. Lacking the ability to function normally or fully: a weak heart.
6. adj. Lacking aptitude or skill: a weak student; weak in math.
7. adj. Lacking or resulting from a lack of intelligence.
8. adj. Lacking persuasiveness; unconvincing: a weak argument.
9. adj. Lacking authority or the power to govern.
10. adj. Lacking potency or intensity: weak sunlight.
11. adj. Linguistics Of, relating to, or being those verbs in Germanic languages that form a past tense and past participle by means of a dental suffix, as start, started; have, had; bring, brought.
12. adj. Linguistics Of, relating to, or being the inflection of nouns or adjectives in Germanic languages with a declensional suffix that historically contained an n.
13. adj. Unstressed or unaccented in pronunciation or poetic meter. Used of a word or syllable.
14. adj. Designating a verse ending in which the metrical stress falls on a word or syllable that is unstressed in normal speech, such as a preposition.
15. adj. Tending downward in price: a weak market for oil stocks.

Century Dictionary and Cyclopedia

1. Bending under pressure, weight, or force; pliant, or pliable; yielding; lacking stiffness or firmness: as, the weak stem of a plant.
2. Lacking strength; not strong. Specifically
3. Deficient in bodily strength, vigor, or robustness; feeble, either constitutionally or from age, disease, etc.; infirm; of the organs of the body, deficient in functional energy, activity, or the like: as, a weak stomach; weak eyes.
4. Lacking moral strength or firmness; liable to waver or succumb when urged or tempted; deficient in steady principle or in force of character.
5. Lacking mental power, ability, or balance; simple; silly; foolish.
6. Unequal to a particular need or emergency; ineffectual or inefficacious; inadequate or unsatisfactory; incapable; impotent.
7. Incapable of support; not to be sustained or maintained: unsupported by truth, reason, or justice: as, a weak claim, assertion, argument, etc.
8. Deficient in force of utterance or sound; having little volume, loudness, or sonorousness; low; feeble; small.
9. Not abundantly or sufficiently impregnated with the essential, required, or usual ingredients, or with stimulating or nourishing substances or properties; not of the usual strength: as, weak tea; weak broth; a weak infusion; weak punch.
10. Deficient in pith, pregnancy, or point; lacking in vigor of expression: as, a weak sentence; a weak style.
11. Resulting from or indicating lack of judgment, discernment, or firmness; arising from want of moral courage, of self-denial, or of determination; injudicious: as, a weak compliance; a weak surrender.
12. Slight; inconsiderable; trifling.
13. (I) In grammar, infiected— as a verb, by regular syllabic addition instead of by change of the radical vowel;
14. as a noun or an adjective, with less full or original differences of case-and number-forms: opposed to strong (which see).
15. Poorly supplied; deficient: as, a hand weak in trumps.
16. Tending downward in price: as, a weak market; corn was weak.
17. To make weak; weaken.
18. To soften.
19. To become weak.

Wiktionary

1. adj. Lacking in force (usually strength) or ability.
2. adj. Dilute, lacking in taste or potency.
3. adj. grammar Displaying a particular kind of inflection, including:
4. adj. physics One of the four fundamental forces associated with nuclear decay.
5. adj. slang Bad or uncool.

GNU Webster's 1913

1. adj. Wanting physical strength.
2. adj. Deficient in strength of body; feeble; infirm; sickly; debilitated; enfeebled; exhausted.
3. adj. Not able to sustain a great weight, pressure, or strain.
4. adj. Not firmly united or adhesive; easily broken or separated into pieces; not compact.
5. adj. Not stiff; pliant; frail; soft.
6. adj. Not able to resist external force or onset; easily subdued or overcome.
7. adj. Lacking force of utterance or sound; not sonorous; low; small; feeble; faint.
8. adj. Not thoroughly or abundantly impregnated with the usual or required ingredients, or with stimulating and nourishing substances; of less than the usual strength.
9. adj. Lacking ability for an appropriate function or office.
10. adj. Not possessing or manifesting intellectual, logical, moral, or political strength, vigor, etc.
11. adj. Feeble of mind; wanting discernment; lacking vigor; spiritless.
12. adj. Resulting from, or indicating, lack of judgment, discernment, or firmness; unwise; hence, foolish.
13. adj. Not having full confidence or conviction; not decided or confirmed; vacillating; wavering.
14. adj. Not able to withstand temptation, urgency, persuasion, etc.; easily impressed, moved, or overcome; accessible; vulnerable.
15. adj. Wanting in power to influence or bind.
16. adj. Not having power to convince; not supported by force of reason or truth; unsustained.
17. adj. Wanting in point or vigor of expression.
18. adj. Not prevalent or effective, or not felt to be prevalent; not potent; feeble.
19. adj. 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.
20. adj. (Stock Exchange) Tending towards lower prices.
21. adj. 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).
22. adj. Pertaining to, or designating, a noun in Anglo-Saxon, etc., the stem of which ends in -n. See Strong, 19 (b).
23. adj. (Stock Exchange) Tending toward a lower price or lower prices.
24. adj. (Card Playing) Lacking in good cards; deficient as to number or strength.
25. adj. (Photog.) Lacking contrast.
26. v. rare To make or become weak; to weaken.

WordNet 3.0

1. adj. lacking bodily or muscular strength or vitality
2. adj. wanting in moral strength, courage, or will; having the attributes of man as opposed to e.g. divine beings
3. adj. (used of vowels or syllables) pronounced with little or no stress
4. adj. (used of verbs) having standard (or regular) inflection
5. adj. wanting in physical strength
6. adj. deficient in magnitude; barely perceptible; lacking clarity or brightness or loudness etc
7. adj. deficient in intelligence or mental power
8. adj. deficient or lacking in some skill
9. adj. not having authority, political strength, or governing power
10. adj. overly diluted; thin and insipid
11. adj. tending downward in price
12. adj. likely to fail under stress or pressure