middle age
US /ˌmɪd.l̩ ˈeɪdʒ/
UK /ˌmɪd.l̩ ˈeɪdʒ/

1.
edad media, mediana edad
the period of life between youth and old age, usually considered to be between the ages of 45 and 65
:
•
He's in his middle age, but still very active.
Está en la edad media, pero sigue siendo muy activo.
•
Many people experience a 'midlife crisis' during middle age.
Muchas personas experimentan una 'crisis de la mediana edad' durante la edad media.