—n. 1. a cardinal number, ten times six.
2. a symbol for this number, as 60 or LX.
3. a set of this many persons or things.
4. sixties,the numbers, years, degrees, or the like, from 60 through 69, as in referring to numbered streets, indicating the years of a lifetime or of a century, or noting degrees of temperature: Her grandfather is in his late sixties. The temperature is in the low sixties. 5. like sixty,Informal.with great speed, ease, energy, or zest: Everyone was working like sixty to finish up before the holidays.