noun
A party where participants wear costumes and dance, often themed around anime, manga, or game characters.
See also: コスプレ
今週末、秋葉原でコスプレダンスパーティーが開かれる。
A cosplay dance party will be held in Akihabara this weekend.
Spelling with interpuncts, sometimes used for clarity.
コスプレ refers to costume play in general, while コスプレダンスパーティー specifically combines cosplay with a dance party event.
Wasei-eigo compound from English 'cosplay' (costume play) + 'dance' + 'party'.