Adjective

(er)

Lacking in force (usually strength) or ability.

* Shakespeare

a poor, infirm, weak , and despised old man

* Dryden

weak with hunger, mad with love

Unable to sustain a great weight, pressure, or strain.

a weak''' timber; a '''weak rope

Unable to withstand temptation, urgency, persuasion, etc.; easily impressed, moved, or overcome; accessible; vulnerable.

weak''' resolutions; '''weak virtue

* Joseph Addison, The Fair Petinent Act I, scene I:

Guard thy heart / On this weak side, where most our nature fails.

Dilute, lacking in taste or potency.

*

, title=The Mirror and the Lamp , chapter=2 citation , passage=That the young Mr. Churchills liked—but they did not like him coming round of an evening and drinking weak whisky-and-water while he held forth on railway debentures and corporation loans. Mr. Barrett, however, by fawning and flattery, seemed to be able to make not only Mrs. Churchill but everyone else do what he desired.}}

(grammar) Displaying a particular kind of inflection, including:

# (Germanic languages, of verbs) Regular in inflection, lacking vowel changes and having a past tense with -d- or -t-.

# (Germanic languages, of nouns) Showing less distinct grammatical endings.

# (Germanic languages, of adjectives) Definite in meaning, often used with a definite article or similar word.

(physics) One of the four fundamental forces associated with nuclear decay.

(slang) Bad or uncool.

(mathematics, logic) Having a narrow range of logical consequences; narrowly applicable. (Often contrasted with a statement which implies it.)

Resulting from, or indicating, lack of judgment, discernment, or firmness; unwise; hence, foolish.

* Milton

If evil thence ensue, / She first his weak indulgence will accuse.

Not having power to convince; not supported by force of reason or truth; unsustained.

The prosecution advanced a weak case.

* Milton

convinced of his weak arguing

Lacking in vigour or expression.

a weak''' sentence; a '''weak style

Not prevalent or effective, or not felt to be prevalent; not potent; feeble.

* Shakespeare

weak prayers

(stock exchange) Tending towards lower prices.

a weak market

Adjective

(head)

Unskilled, lacking normally expected degree of ability.

Having an incompetent lawyer may be grounds for a retrial, but the lawyer in question probably doesn't know that.

Unable to make rational decisions, insane or otherwise cognitively impaired.

The charged was judged incompetent to stand trial, at least until his medication started working.