Idioms and Phrases with by coincidence
Through an accidental simultaneous occurrence, as in By coincidence both researchers discovered the same solution. [Mid-1600s] Also see by chance.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.