Which term means 'to gradually decrease speed'?

The term that means 'to gradually decrease speed' is ritardando. This term is commonly used in musical scores to indicate that the performer should slow down the tempo of the piece gradually. Ritardando is typically indicated with the abbreviation 'rit.' and is essential for conveying expressive nuances in music, allowing for moments of tension, emotional depth, or a softening of the musical line.

Rallentando also refers to a slowing down, but it often implies a more pronounced or immediate decrease in speed compared to ritardando. Quasi means 'almost' or 'as if,' and poco translates to 'a little.' Neither of these terms relates to tempo changes, making them unsuitable for this specific definition.