From WordNet (r) 3.0 (2006) [wn]:
racing
n 1: the sport of engaging in contests of speed
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Race \Race\, v. i. [imp. & p. p. Raced (r[=a]st); p. pr. & vb.
n. Racing (r[=a]"s[i^]ng).]
1. To run swiftly; to contend in a race; as, the animals
raced over the ground; the ships raced from port to port.
[1913 Webster]
2. (Steam Mach.) To run too fast at times, as a marine engine
or screw, when the screw is lifted out of water by the
action of a heavy sea.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Racing \Ra"cing\ (r[=a]"s[i^]ng),
a. & n. from Race, v. t. & i.
[1913 Webster]
Racing crab (Zool.), an ocypodian.
[1913 Webster]