Meaning of “weak” - Learner’s Dictionary

weak

adjective us uk /wiːk/
His legs were weak.The disease had left him feeling weak.The prisoner was too weak to stand.He had become increasingly weak as he got older.People who lack sufficient food lose weight and grow weak.
BODY

B1 not physically strong:

He felt too weak to sit up.
The children were weak with/from hunger.
CHARACTER

B2 not powerful, or not having a strong character:

LIKELY TO FAIL

likely to fail:

a weak economy
a weak team
LIKELY TO BREAK

B2 likely to break and not able to support heavy things:

a weak bridge
TASTE

B2 A weak drink has little taste or contains little alcohol:

REASON

B2 A weak reason or excuse is one that you cannot believe because there is not enough proof to support it.

NOT GOOD

B1 not good at something:

She reads well but her spelling is weak.
SLIGHT

B2 difficult to see or hear:

He spoke in a weak voice.
a weak light
weakly adverb

(Definition of “weak” from the Cambridge Learner’s Dictionary © Cambridge University Press)