Other forms: accelerandos
The instruction accelerando in a piece of music tells you to gradually up the tempo. In other words, start singing or playing a little bit faster and slowly continue to increase the speed.
Accelerando is an Italian word meaning "gradually speeding up." The word is related to the English word accelerate, "to gain speed." Both words come from the Latin verb accelerare, "to quicken." The -ando and -endo suffixes in Italian indicate a gradual process of change; the related (but opposite) meaning of ritardando is "gradually slowing down." Accelerando can name or describe a piece of music, or it can describe how a piece should be performed.