A flexible object or material can be bent easily without breaking. 柔韧的
adjective [原级]灵活的;柔韧的,易弯曲的
The flexibility of the lens decreases with age; it is therefore common for our sight to worsen as we get older. 眼球晶状体的柔韧性随着年龄的增长而降低;因此普遍的情况是随着我们年纪变老,我们的视力就会变差。