Put one’s finger on something is an idiom that has been in use for decades. We will examine the meaning of the idiom put one’s finger on something, where it came from, and some examples of its idiomatic usage in sentences.
To put one’s finger on something means to identify something, to find the cause of something, to understand something, to remember something. The idiom put one’s finger on something came into use in the latter-1800s. The expression calls up the image of looking through a document and literally placing one’s finger on the words that will support one’s assertion. Often, the phrase is used in the negative, as in “I can’t put my finger on it,” to mean one cannot identify the cause of something, remember something, or understand something.
It was a rousing talk, but something about it bothered me, though I could not quite put my finger on it. (The Hawaii Catholic Herald)
It’s tough to put my finger on what was wrong with it, namely because I don’t have enough fingers for the job. (The Cascadia Weekly)
“I can’t put my finger on what the ramifications would be, but if we significantly underreport there probably will be some ramification, especially financially,” Carter said. (The Lynchburg News & Advance)