This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. A small cassette containing a single track of popular music on each side

"Doing some fall closet cleanout over the weekend, I came across a stack of old cassingles -- oh how the word 'cassingle' warms my heart -- and decided it was time to make like Beyoncé and Jay-Z and upgrade"