Definition of “weak”

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. 1. not functioning as well as normal  ⇒ weak eyes 
   2. 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 
    1. 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 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
    2. 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. photography having low density or contrast; thin
14. (of an industry, market, currency, securities, etc) falling in price or characterized by falling prices