a finish of a race in which two or more contestants are so close to the finish line that reference to a photograph of the finish is necessary to determine the winner.
Origin of photo finish
First recorded in 1935–40
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
a finish of a race in which contestants are so close that a photograph is needed to decide the result
any race or competition in which the winners or placed contestants are separated by a very small margin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012