Weak

adjective, weaker, weakest.
1.
not strong; liable to yield, break, or collapse under pressure or strain; fragile; frail:
a weak fortress; a weak spot in armor.
2.
lacking in bodily strength or healthy vigor, as from age or sickness; feeble; infirm:
a weak old man; weak eyes.
3.
not having much political strength, governing power, or authority:
a weak nation; a weak ruler.
4.
lacking in force, potency, or efficacy; impotent, ineffectual, or inadequate:
weak sunlight; a weak wind.
5.
lacking in rhetorical or creative force or effectiveness:
a weak reply to the charges; one of the author’s weakest novels.
6.
lacking in logical or legal force or soundness:
a weak argument.
7.
deficient in mental power, intelligence, or judgment:
a weak mind.
8.
not having much moral strength or firmness, resolution, or force of character:
to prove weak under temptation; weak compliance.
9.
deficient in amount, volume, loudness, intensity, etc.; faint; slight:
a weak current of electricity; a weak pulse.
10.
deficient, lacking, or poor in something specified:
a hand weak in trumps; I’m weak in spelling.
11.
deficient in the essential or usual properties or ingredients:
weak tea.
12.
unstressed, as a syllable, vowel, or word.
13.
(of Germanic verbs) inflected with suffixes, without inherited change of the root vowel, as English work, worked, or having a preterit ending in a dental, as English bring, brought.
14.
(of Germanic nouns and adjectives) inflected with endings originally appropriate to stems terminating in -n, as the adjective alte in German der alte Mann (“the old man”).
15.
(of wheat or flour) having a low gluten content or having a poor quality of gluten.
16.
Photography. thin; not dense.
17.
Commerce. characterized by a decline in prices:
The market was weak in the morning but rallied in the afternoon.
adjective
1.
lacking in physical or mental strength or force; frail or feeble
2.
liable to yield, break, or give way: a weak link in a chain
3.
lacking in resolution or firmness of character
4.
lacking strength, power, or intensity: a weak voice
5.
lacking strength in a particular part: a team weak in defence
6.

not functioning as well as normal: weak eyes
easily upset: a weak stomach

7.
lacking in conviction, persuasiveness, etc: a weak argument
8.
lacking in political or strategic strength: a weak state
9.
lacking the usual, full, or desirable strength of flavour: weak tea
10.
(grammar)

denoting or belonging to a class of verbs, in certain languages including the Germanic languages, whose conjugation relies on inflectional endings rather than internal vowel gradation, as look, looks, looking, looked
belonging to any part-of-speech class, in any of various languages, whose inflections follow the more regular of two possible patterns Compare strong (sense 13)

11.
(of a syllable) not accented or stressed
12.
(of a fuel-air mixture) containing a relatively low proportion of fuel Compare rich (sense 13)
13.
(photog) having low density or contrast; thin
14.
(of an industry, market, currency, securities, etc) falling in price or characterized by falling prices