To a young, single Korean woman, it's a curse word they hope to never be called in life.

It does NOT mean maid. I often hear people say, "I have an ajuma" and Koreans get confused because they don't know if the person is referring to a wife or something else.

It is technicaly defined as "Mrs." like Ajushee is a "Mr." Again, like the Ajushee post I had earlier, the "depreciative" aspect applies; but not only in a social class kind of way...in the appearance sort of way, mostly.

Over my years in Korea, here's what I gathered...
An Ajuma is...a married woman with children who appears in her mid 30's and above. Of course, you can't just tell by the look of a woman whether or not she is married with children and over 40, right? In my opinion, an Ajuma meets these aspects:
1. A little overweight (and above)
2. Appears to have lost the will to appear attractive
3. Cannot appear attractive, no matter how hard she tries
4. Usually short haired...commonly permed into an afro
5. Just...very loud when speaking...especially w/ other ajumas (no shame)

I know some of these aspect sounds a bit mean and offensive, but we're in a culture where appearances are everything, so it is common. And I'm willing to bet the Korean people would say, "Yeah, he's right." This is why you may notice the pretty women are always called "Ah-Gah-Shee" and the sort of unattractive ones are "Ajuma" or "Ah-Joo-Muh-Nee" (a tad bit more formal way of Ajuma, but still the same meaning), regardless of age or marital status.

TIP: it is best to never, ever use that word to a girl who you may notice is trying really hard to stay attractive. By saying that to her means she is ugly and it'll probably make her cry at night.

Excellent Post! All please note. I'm older, but not wiser when it comes to this gentleman's understanding of the culture! I'm recommending eddiev9 for an upgrade in reputation. Watch for a color change soon!
I especially liked the addition of "she might cry..." It is so true. Lime

Reputation upgrade??? Change in color??? Wohooo!! So how much money will I receive in the mail?

Just kidding! Thanks!
It's surprising how these little things take so many years of experience to figure out.