A Cappella? Is That How You Spell It? The phrase a cappella is among the most butchered and misunderstood musical terms. The predominant, and most "correct" spelling, is ... a cappella - two words, two "p's", two "l's." A Cappella, A Picky Definition Musicologists have fun debating the extent to which a cappella, 'in the style of the chapel,' can include instrumental accompaniment. Some argue that early sacred a cappella performances would sometimes include instruments that double a human voice part. So, the correct definition of a cappella s ....