Why is “Fido” a common name for a dog?

Dear Cecil: How did Fido become the more or less generic name for the family dog, when in fact there are few canines that actually answer to that moniker? N.D.G., Chicago

Cecil replies:

If you’d been properly educated, N., you wouldn’t have to ask this question. Then again, if you and the rest of the boomers already knew the easy stuff, this job might actually become strenuous. Fido comes from the Latin fidus, faithful, a fitting term for man’s best friend. Or at least it was back in the days when four years of high school Latin was considered the bare minimum for a person of culture (hey, I took it). Fidus of course will be familiar to the many readers of Virgil’s Latin epic the Aeneid, from the expression fidus Achates, faithful Achates, Achates being the character who played Pancho to the heroic Aeneas’s Cisco Kid.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.