I read this term in an online article and it was referring to people. I assume it means elderly people. Is there an age that one must be to use this term?
It appears to depend upon which organization or company is assigning the designation. Usually using 65 to 70 years of age as a lower threshold. This is similar to varying ages for 'senior discounts' (in the US anyways).
Here is a page from NTT Facilities Research, which lists a few terms regarding the elderly relative to age.