The body's ability to defend against illness and infection; the overall strength of the immune system, which can vary with lifestyle and age.
十分な睡眠は免疫力を高めるのに大切だ。
Adequate sleep is important for boosting immune strength.
栄養バランスの良い食事で免疫力を維持しよう。
Maintain your immunity with a well-balanced diet.
高齢になると免疫力が低下しやすい。
Immune strength tends to decline with age.