'Scratch race' definitions:

Definition of 'scratch race'

(from WordNet)
noun
A race in which all contestants start from scratch (on equal terms)

Definition of 'Scratch race'

From: GCIDE
  • Scratch \Scratch\, a. Made, done, or happening by chance; arranged with little or no preparation; determined by circumstances; haphazard; as, a scratch team; a scratch crew for a boat race; a scratch shot in billiards. [Slang] [1913 Webster]
  • Scratch race, one without restrictions regarding the entrance of competitors; also, one for which the competitors are chosen by lot. [1913 Webster]