Why do we say Uncle, rather than Uncle-in-law?

[Paulo Leeds]

Is the word "uncle-in-law" ever used when talking about the husband married to your mother's sister?

Or is this person typically still called your "uncle", even though the person is not a blood relative?

Seems strange that an Uncle by blood, and an Uncle by marriage would have the same title...

[CaroleW]

Is the word "uncle-in-law" ever used

"Oh - hello Uncle in law John - how are you"

No - I can't really see it taking off can you?  Have you ever hear it used - would you use it yourself?

What about honorary uncles and aunts who are just close family friends?  Do we greet them  - "hello honorary aunt/uncle" 

Accept it's just uncle/aunt or christian names

[mrsruz]

Rather too much of a mouthful I would think.

[Mike in Cumbria]

Uncle in law would be quite a mouthful but you're right - Uncle or Aunt are ambiguous terms and can mean one of two things (and that's not including all the honorary aunts and uncles that many families acquire!)

[Paulo Leeds]

So why do we use father-in-law very commonly?

Also until you reach a certain age, you probably think your Uncle by marriage is as close a relation to you as your Uncle by blood...

[Mart 'n' Al]

I think this is a very good question. It is irrelevant that it sounds like a mouthful when you say uncle in law John, as you would never use it in that form. You never address your mother in law as mother-in-law Susan or mother-in-law Mrs Smith.

Martin

[rosie99]

The Oxford dictionary has
Uncle - NOUN - The brother of one's father or mother or the husband of one's aunt.

English Language is a strange thing, I hate as a female being addressed as a 'Guy(s)'   after all 'Guy' is male why should 'Guys'  be both sexes.

[Paulo Leeds]

My point is the equal footing an Uncle by blood gets with an Uncle by marriage.

is it not the same as calling your Mother-in-law 'Mum' ??

[Mike in Cumbria]

My point is the equal footing an Uncle by blood gets with an Uncle by marriage.

is it not the same as calling your Mother-in-law 'Mum' ??

Yes, exactly the same. Some people do call their in-laws Mother and Father, and I'm pretty sure that this was much more common in the past.