[1] : The Collaborative International Dictionary of English v.0.48

accelerando \accel`eran"do\, a. it. mus.
   gradually accelerating the movement.
   1913 webster

[2] : WordNet (r) 2.0

accelerando
     adj : gradually increasing in tempo
     n : a gradually increasing tempo of music; "my ear will not
         accept such violent accelerandos"
     adv : with increasing speed; "here you must play accelerando"

Accelerando >> A Words
Accelerando, definition of term: Accelerando
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