虚弱 (xū ruò): yếu kém

After recovering from a serious illness, his body was still very weak; he would gasp for breath even after walking a few steps, and the doctor advised him to rest more and gradually regain his strength.

After working overtime for a month straight, she felt weak and powerless, and even getting up made her dizzy, so she had to ask for leave and rest at home.

The baby was born prematurely and was very weak, needing to stay in an incubator for a while; only after gaining weight and stabilizing all indicators could it go home.

As the elderly man aged, his body became increasingly weak; even a slight chill would give him a cold, so his family paid special attention to weather changes and added clothes for him promptly.

On the second day after surgery, the patient was still very weak and spoke in a low voice; the nurse adjusted his pillow to help him breathe comfortably.