Someone who is considerably younger than the other partner, and is a sexual lover, or personal employee.
Not confined to the homosexual lifestyle.
Can refer to a young male partner of a much older female partner.
Generally, it refers simply to a much younger male partner, to an older person.
The older person is considered to be considerably older, by not just a few years, but usually more than is considered normal.
The attraction is usually based on the older person's ability to provide certain benefits, other than sexual, such as money, accommodation, etc., for which the younger male provides sexual relief.