The terms private eye and gumshoe have the same definition. We will look at the meaning of the words private eye and gumshoe, where the terms came from and some examples of their use in sentences.
A private eye is a slang term for a private detective or a private investigator. A popular but probably untrue story about the origin of the term private eye concerns the Pinkerton Detective agency, established in Chicago in the 1850s. The agency’s logo was an open, unblinking eye. However, the term private eye meaning a private investigator doesn’t show up until the 1930s, in stories written by Raymond Chandler. Most probably, the term private eye is a humorous reference to the first letter of the word investigator, which when spoken may be interpreted as the word eye. Private eye is an open compound word, which consists of two words that are used together to form a new meaning, yet a space is maintained between them.
The word gumshoe is also a slang term for a private detective or a private investigator. In this case, the word gumshoe references a type of shoe that was invented in the late 1800s. Gumshoes were foot apparel with gum rubber soles. Previously, shoes had leather shoes. It was much easier for a man wearing a shoe with a silent, gum rubber sole to surveille a subject, undetected. Gumshoe is a closed compound word, which consists of two words used together without a space or hyphen between them, in order to form a new meaning.
She argued that hiring a private eye to investigate your partner is “just as bad as cheating” and that people “become private eyes in their own relationships.” (The Irish Independent)
In a time of enormous financial pressures for print journalism the dedication of The Times’ reporters and editors to old fashioned gumshoe investigations such as Trump’s tax deductions is a service to us all. (Forbes Magazine)