To age; to grow old (especially in appearance); to look older or show signs of aging.
最近、彼は急に老けたように見える。
Lately he looks like he has aged suddenly.
忙しさで彼女は少し老けてしまったと友達が言った。
Her friends said she looked a bit older because of the stress/busyness.
役のために髪を白くして老け役を演じた。
She whitened her hair for the role to play an older character.