People who are so obviously
gay but aren't telling it. There is a difference between just "in the closet" and "in the GLASS closet".
Those just "in the closet" have speculations circulating around them
gay - whether'd about their mannerism or personality, but they're not really pushing their gayness. They
will tend to have opposite gender "partners", but many people
will conclude that they're just beards/fake.
Those in the "glass closet" are walking and breathing of gayness - e.i., they
will be always walking with that one same gendered partner, they adopt children and they might even be reported living with the partner, but they'll never say they're
gay or straight.
Queen Latifah, Jodie Foster, Anderson
Cooper, Kevin Spacey,
Victor Garber (Mr Andrews - the Titanic
guy) & Fiona Shaw (Harry Potter's Aunt Petunia) are in the glass closet.