A. weaken
B. mend
C. entreat
D. corrupt

Explanation:

The word impair means to damage something or make it weaker, worse, or less effective.

In simple words: to reduce strength, quality, or ability.

So, the synonym of impair is weaken.

Real-Life Example

• Poor sleep can impair your concentration.
• Poor sleep can weaken your concentration.

Impair = Weaken

Why “weaken” is correct

• Impair means to reduce strength or function.
• Weaken means to make something less strong or effective.
• Both words express loss of ability or quality.

Main Points for Exams

• Impair means to damage or reduce effectiveness.
• Weaken is its correct synonym.
• It is often used in health, ability, or system performance contexts.
• Therefore, Weaken is the correct answer.
• Frequently asked in PPSC, FPSC, CSS, PMS, NTS, IELTS, and TOEFL vocabulary tests.

Quick Memory Trick

💪 Impair = Reduce Strength
🧠 Weaken = Same Meaning

Strengthen ↔ Improve
Damage ↔ Impair = Weaken ✔️