The Collaborative International Dictionary of English v.0.48:

Diabolo \Di*ab"o*lo\ (d[i^]*[a^]b"[-o]*l[=o]), n.
   An old game or sport (revived under this name) consisting in
   whirling on a string, fastened to two sticks, a small
   somewhat spool-shaped object (called the diabolo) so as to
   balance it on a string, toss it in the air and catch it, etc.
   [Webster 1913 Suppl.]