The term SCAT, CAT! is a reference to the jazz vocal style of scat singing. Scat singing is a form of vocal improvisation that involves singing nonsense syllables and words. The two crossword solutions for this term are SHOO (4 letters) and ELLA (4 letters). These two names refer to two of the most famous scat singers in history: Louis Armstrong and Ella Fitzgerald. Armstrong's nickname was 'SATCHMO' and he was known for his signature scat singing style. Fitzgerald was also a renowned scatter singer and was known for her ability to improvise complex melodies.