The only possibly implied word I can think of is “conjugal,” but how is that funny? That a husband and wife are “yoked” together is too commonplace an image to be the basis for a joke, ISTM. When a marriage didn’t work out it was common in the 19th Century to say, “The horses wouldn’t draw together” – the phrase used by Josiah Bounderby in Dickens’ Hard Time to describe the apparently impending breakup of his marriage to Gradgrind’s daugher Louisa.
It took me a second to get it, but it’s an oral sex joke… I think. “Yoke” can be matrimonial slang, and in Latin the word “yoke” is “jugum”, pronounced “joo’ -gum” - or to the punster “you gum”. That implies implies oral sex, which is surely one of the cornerstones of marriage. The punchline is the following:
“Yoke” implies a heavy burden rather than a simple connection. Russians still refer to their years of subjugation under the Mongols as “The Tatar Yoke.”
The implication is that a married man is a slave under the yoke of his wife.
To “jug” means to send to jail. I think Bierce is making a play on words. “Jugum” sounds like “jug 'em.” Comparing marriage to imprisonment is not unusual. Think of the use of “the old ball & chain” as a slang term for a spouse.
Another vote for the heavy burden theory. There is a longstanding usage of yoke in that manner. In the times of King James, for example: “Take my yoke upon you, for it is light and easy to bear.” — Jesus
Yet another vote for “heavy burden”. It’s a play on "yoke"s meanings of “connect together” and also “to burden”. Note also the overly polite language of the definition. It sounds like a sarcastically polite imitation of a henpecked man.
ETA: Apparantly, “jugum” was also the name of a Roman tax. Cite
Having reviewed all posts, I think the word Bierce was referring to is “subjugate.” I don’t think it has anything to do with oral sex; even an elliptical mention of that would have been unprintable in Bierce’s day.
The Latin word jugum (related to the verb jungere - “to join”) has an old, literal meaning of “The yoke used for oxen” (hauling and plowing with oxen was far more common in the ancient world than with horses or even mules).
Like many agriculturally-based terms in Latin (e.g. pecus -> pecunia), the word and associated action was applied to more abstract situations. Vanquished enemy armies, for example, were often forced to march under a makeshift gateway as a sign of humiliation. This gateway was called a jugum, and hence the word also has the connotation of “humiliation”. The Romans also used the word to refer to the bonds of slavery and, yes, even marriage.