The term 'Improvises Nonsense Syllables' can be summarized by the crossword solution SCATS, which stands for 'Soloing with Cockney Accent and Tongue Slurs'. This is a type of vocal improvisation that originated in jazz music, where a singer would use nonsense syllables to create a unique sound. It is often used to add texture and complexity to a song, and has been popularized by many jazz singers such as Ella Fitzgerald and Louis Armstrong.