n. One who is between the age of 50 and 59, inclusive.
adj. Being between the age of 50 and 59, inclusive.
adj. Of or relating to a quinquagenarian.
The Century Dictionary and Cyclopedia
Being fifty years of age.
n. A person aged fifty or between fifty and sixty.
Word Usage
"Newsweek resurrected this idea with its cover "Diana at 50," complete with Photoshopped pictures of the quinquagenarian princess in contemporary scenes."