Q: The word “gentleman” is so loosely used these days that it’s now meaningless. For example, a witness will refer to the perpetrator of a crime as “the gentleman wielding the gun.” Is this correct usage?
A: I may be old-fashioned, but I’m a lady who thinks of a gentleman as, well, a gentleman.
Nevertheless, the word “gentleman” has had many meanings since it first showed up in English (as “gentile man”) in the 13th century. Many of these senses have had nothing to do with a man who is well-born or well-mannered.
When the word originally appeared, according to the Oxford English Dictionary, it referred to a man of gentle (that is, noble) birth.
Over the years, it came to mean a man distinguished by social position, good manners, independent wealth, and so on. However, the word also took on many not-so-gentlemanly meanings.
For example, “visiting the gentlemen’s” has meant going to the men’s room. A superior racing horse has been referred to as “quite the gentleman.” And “the old gentleman in black” has meant the Devil.
Since the 16th century, according to OED citations, the term “gentleman” has been used to refer politely to men of all classes. And since the 17th century, it’s been used humorously to refer to men of less than exalted social standing.
However, I wouldn’t use the word “gentleman” in the sense you mention (to refer to the perpetrator of a crime), except perhaps in jest.
I don’t find this sense of the word in the OED or in the two US dictionaries I consult the most: The American Heritage Dictionary of the English Language (4th ed.) and Merriam-Webster’s Collegiate Dictionary (11th ed.).
The usage sounds to me like the kind of jargon one might encounter on a police blotter.
Aside: One of my favorite gentlemen in English literature is Mr. Darcy of Jane Austen’s Pride and Prejudice. But another old favorite is actually a gentleman’s gentleman – the valet Jeeves in P. G. Wodehouse’s Bertie Wooster novels.