noun, noun which may take the genitive case particle 'no'
middle age; midlife
Refers to the period of life roughly between 40 and 60 years old. Can be used as a noun or as a no-adjective to describe things related to middle age.
He started paying attention to his health after reaching middle age.
中年の男性が公園でジョギングをしている。
A middle-aged man is jogging in the park.
Before I knew it, I had become middle-aged.
He is approaching middle age.
He seems to be going through a midlife crisis.
middle-age spread; weight gain in middle age
mid-life crisis