How has the word 'Post Modern' been used by different 'theorists'

Theodor Adorno, Hermann Broch and Clement Greenberg all used Kitsch art

• Adorno perceived this in terms of what he called the cutlure industry where the art is controlled and formulated by the needs of the market and given to a passive population which accepts it. He claimed that kitsch is parody of catharis and a parody of aesthetic experience.
• Broch called kitsch "the evil within the value-system of art"—that is, if true art is "good", kitsch is "evil".
• This position is adopted by both defenders of modernism such as Clement Greenberg as well as radical opponents of modernism such as Félix Guattari, who calls it modernism's "last gasp".

The term "Pop Art" was used by Lawrence Alloway to describe paintings that celebrated consumerism of the post World War II era.