Idioms and Phrases with put the finger on
put the finger on
Inform on, as in The witness put the finger on the defendant. [Slang; c. 1920] Also see put one's finger on.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.