themeless
/ˈθiːmˌlɛs/Definitions
1. adjective
having no theme or unifying idea
“The exhibition’s themeless layout confused many visitors.”
2. adjective
lacking a theme or central idea in music or art
“The jazz ensemble’s themeless improvisation was mesmerizing.”
3. adjective
having no particular or special theme
“The holiday decorations were themeless and colorful.”