The Devil’s Dictionary says that an omen is:

A sign that something will happen if nothing happens.

The Oxford English Dictionary tells us that that omen came into English only in 1582 but that it comes from classical Latin where it also had a meaning of something that foreshadows an event.

The OED frustratingly says that there are lots of theories about the etymology of the Latin word, and then doesn’t tell us any of them.

It does pointedly dismiss the idea that the “o” in omen relates to os meaning “mouth” as if an omen speaks to us. None of the other sources give us much to go on etymologically so that’s not a good omen.

The second citation for omen in the OED is from Ben Jonson, that contemporary of Shakespeare’s and so it gives me an opportunity to talk about old Ben and the times he lived in.

If you get a chance to look at any of the portraits of Ben Jonson that are available say at Wikipedia or Britannica, you might get the impression that the guy was possibly quite physically powerful. I think this was likely the case since the records seem to indicate that started out as a bricklayer and during his life seems to have killed two people in hand to hand combat.

The first of these is pretty telling. Before his career in theatre he went over to Holland as a soldier. He’d have had a good education by that point but wasn’t from an aristocratic background so was likely a common soldier. But there is one account of him standing as the champion in a one-on-one fight that was an ancient contest intended to avoid whole groups of soldiers battling it out. By Jonson’s time it was rarely used but he seems to have been the chosen fighter and to have won, afterward having the honor to claim his opponent’s arms in victory.

The fact that he got selected for the task must have put him in the big-tough-guy category.

Further evidence is that later in life he was jailed for killing another actor in a duel. He later told a friend that the other guy had challenged him to the duel, had used a sword ten inches longer than his own, and had managed to slash Jonson’s arm before Jonson got the better of him.

So at the time of Johnson’s life 400 years ago, single-combat warfare seems still to have been occasionally used and the fighting of duels was pretty common.

But killing someone in a duel wasn’t exactly approved of in law back then. Jonson almost hanged because of it, but was saved by some sympathetic churchman who got him off the hook by converting him to Catholicism and having him recite some apologetic prayers. He also had to go around after this with a brand on his thumb that told everyone that he was a convicted felon.

In between these two deadly events Jonson came to prominence in English theatre. He is said to have been a middling actor but a very good playwright and also an excellent director. He’s described as getting into an arm waving sweaty state of animation in his role as director and I can see actors doing their best to please him if he was the bear of a man I imagine.

As for Jonson’s use of omen we should look to his education. He was lucky enough not only to have been noticed when on death row, but also years before when only about seven he was recommended to Westminster School where he had a strong classical education.

So just as the word omen was emerging from Latin to become an English word we have Jonson likely familiar with it as a Latin word. He’d have been ten years old at the time of that first citation.

There is a legend about Jonson that the more stodgy sources don’t mention so perhaps it’s not true. But it is said that for his first play Jonson approached Shakespeare’s company of players and offered up his manuscript. Whoever read it first was on the point of returning it with a polite thanks-but-no-thanks, when Shakespeare himself just happened to see it lying open, picked it up and thought it pretty good, thereby launching Jonson’s career.

We don’t know if that’s true, but what is true is that Jonson’s tribute to Shakespeare is what heads up the oldest collections we have of Shakespeare’s plays.