Korean terms for family members seem quite overwhelming to those of us trying to learn the language. First of all, there are so many of them. But second of all, Koreans use many of those terms quite freely with people they aren't related to: in particular, because of the social prohbition, under most circumstances, against addressing one's elders by their names, many of the various terms for relatives are used for directly addressing (i.e. talking to, calling out to) older friends and acquaintances. These many "terms of direct address" take the place of the word "you," too, since the various Korean words for "you" seem mostly reserved for advertising copy (e.g. 당신) and talking with children (e.g. 너).
I finally found a blog page that summarizes many of the vocabulary items for relatives and family relations pretty well. I recommend it, but even that summary seems to miss a lot of useful and important information.
For example, during a recent unit on English-language family terms with a fairly low-level 3rd/4th/5th grade class, I realized that they were using the term I had learned meant nephew/niece (조카 [joka]) to mean what we would call "first cousin once removed" (a horrible term – more colloquially we always just said "cousin" in the family reuinion type settings when I was growing up). Which to say, in the term 조카 there is embedded a sort of generational concept.
In researching that word 조카 at an online dictionary, I found some additional complications on it that aren't covered on the above-referenced web page:
처조카 = wife's niece or nephew
조카사위 = niece's husband
조카며느리 = nephew's wife
I'm sure that for almost all of the terms on that webpage, a little research would dig up similar elaborations.
Also, there's a whole other set of terms of direct address that seem to apply to schoolmates and coworkers, only a few of which I can recognize. Many of these are generic job titles, in the vein of 실장님 [siljangnim = "office manager," roughly], which is, for example, the term I should be using for the front-desk-lady at work.
But others aren't really titles at all, but bear on the generational separation between the two individuals: I've recently been becoming aware of 선배 [seonbae] a lot in the Korean drama I'm currently watching – the word means schoolmate or workmate who is "ahead" of one, in seniority terms (it's not clear to me if this is relative seniority or actually years of age – for example, if I'm older but start at a given company later, is someone ahead of me in the seniority chain but younger than me in age a 선배?). It's translated as "senior" but that utterly fails to capture its actual usage.
One thing I've never seen is a truly satisfying list, in one place, of ALL the terms of direct address that Koreans use: mostly when you see someone discussing Korean terms of direct address you get a few examples and then some annoying comment to the effect of: Koreans have hundreds if not thousands of terms of direct address, including names for relatives and titles of coworkers and schoolmates, etc. So my request is: how about a list? I guess it will have to be another little project of mine. Maybe someday.