So the staffing company that put me at my current job has, in the last day or so, decided to place my brother’s girlfriend at the same company. That’s cool, but that brings up a linguistics question:

Is there any analog to “foo-in-law” for serious but non-marital partner relations? In which if any cultures/languages?

Certainly, “my brother’s girlfriend” isn’t oppressive — it’s not significantly more work to produce than, for example, “sister-in-law” would be — but why not something to express more clearly the serious-and-ongoing-non-marital-relationship notion?

Partner fits the mold fairly well, but at this point I feel it’s strongly associated (in US culture, at least) with gay/lesbian relationships — while the phrase “my partner” doesn’t explicitly mark the relationship as homosexual, there’s some semantic spillover. What I’m looking for is something entirely neutral to the sexual question, as fiance is used casually in the US. (If I remember, there are actually two French words here originally, referring to the man and the woman in the engagement and varying slightly in spelling or inflection — two E’s in one, or something. And there’s an accent in there that I’m too lazy to verify and render. Je ne parle pas fran硩s.)

But, of course, this mystery word would be a complement to “fiance”; it would denote a relationship that is explicitly not a formal engagement, one that is not necessarily intended to be a pre-cursor to, but rather potentially simply an alternative to, a traditional engagement and marriage.

The phrase that occured to me as a possible solution: “sister-in-date”. Explicitly dating, explicitly not engaged, implicitly involved in a fairly comfortable and intimate relationship with my brother’s family.

It has the advantage of serving the very specific purpose I have in mind. I don’t know that it’s really all that good, however; I’m having trouble imagining people using it naturally. For one thing, “law” and “date” don’t feel like they match up that well. “law” and “dating” feel more similar, but “sister-in-dating” just sounds awful to me.

I just don’t think I’m cut out to be a professional neologer.