1.
If you describe someone as middle-aged , you mean that they are neither young nor old. People between the ages of 40 and 60 are usually considered to be middle-aged.
...middle-aged, married businessmen.
ADJ
2.
If you describe someone’s activities or interests as middle-aged , you are critical of them because you think they are typical of a middle-aged person, for example by being conventional or old-fashioned.
Her novels are middle-aged and boring.
ADJ [ disapproval ]