How did the term "private dick" for a private investigator originate?

The origin of the term "private dick" for a private investigator is not universally agreed upon, but there are several theories that have been proposed:

Shortened Version of "Detective"

One of the most widely accepted theories is that "dick" is simply a shortened version of the word "detective." This explanation, although logical, does not provide a clear reason for how the full word was shortened to "dick"1.

Romanian Word "dik"

Another theory suggests that the term could have originated from the Romanian word "dik," meaning "to see" or "to watch." In the late 1800s, criminals used "dick" to mean being watched or watching someone closely, which could have been applied to police or private investigators who were known for their surveillance activities13.

Influence of Dick Donovan

A third theory proposes that the term might have been influenced by the fictional character Dick Donovan, a Scottish detective created by Joyce Emmerson Preston Muddock in the late 1800s. This character was a prominent figure in detective literature and could have contributed to the popularization of the term "private dick" to describe professional investigators1.

While these theories exist, none have been universally accepted as the definitive origin of the term "private dick." However, the shortened version of "detective" and the influence of Dick Donovan are among the more commonly cited explanations.