Noun. Female version of the term "Warbler", referring to the fictional a capella group, "The Dalton Academy Warblers" from the popular TV show "Glee". Is also used to describe when a girl makes a cosplay or costume resembling the school uniform of Dalton Academy.
I love the Warblers so much, I consider myself a Warbleret/Warblerette.
Hey, check out her costume, she looks like a Warbleret/Warblerette.