While the exact years that one enters middle age is uncertain, the spelling is very definite.

Middle age, a noun that means someone is about 40 to 65 years old, is two words (like ice cream) with no hyphen. For example: At the end of middle age, most people’s children have left home.

When using the word as an adjective – such as middle-aged – the hyphen appears, though. For example: Los Angeles has many middle-aged singles bars.

And with that, we can retire the issue of spelling of these two words for good.