Which of these musical terms means 'slow down'?

In music the word 'ritardando' means to 'slow down'.

Musical tradition is at times a rather odd element of this popular art. One of those traditions that still holds true for today is that of using Italian terms to instruct a performer in notated scores. As you might very well expect, the use of Italian stems from the important influence that the Italians had on Western Classical Music from the Medieval days forward.

The Italians shaped and developed music and the instruments involved in a way that very few other countries have. It is perhaps this legacy that has led to the use of Italian in music for many hundreds of years and something that every student of the subject needs to embrace.

The word 'ritardando' is an Italian word that regularly appears in music. It is a word that tells the performer or player to alter the speed of the passage they are playing. Often the word is abbreviated in written scores to 'rit.'.

The word 'ritardando' indicates to the performer to slow down the speed of the passage they are playing. This may be a purely expressive gesture or one that leads the music into a different section that is at a slower speed.