"Ele é meu irmão mais novo."

Translation: He is my younger brother.

[frozen3v0lution]

Certainly "He is my newest brother" means the same thing, and in my opinion even translates more directly.

[inshadeone]

A brother isn't an item just brought from a shop though ;). On a serious note though - no, it sounds very weird to say "newest brother" in English. You can say "newborn brother" if you just had one born into the family, but within some days it would change to younger (correct for this exercise's sentence) or youngest.
The only context you might use "newest brother" (besides it being a bit of a joke about a newly born brother) in could be if you acquire one through adoption into the family and it's not the first time this happens. The first time you could conceivably say "he is my new brother", and for any consequitive brother you can then say "the newest".

[Danmoller]

Adding....

The expression "irmão mais novo" does mean "younger brother".

If you want to say the weird "newest brother" (as if you're getting a lot of brothers and this is the your latest "achievement"), then you'd say "o meu mais novo irmão".

[WaynK8]

Because Duo sometimes gives non-sensical sentences, I went with the flow and wrote "newest brother". Thanks for the clarification.

[Ouwetoffie1]

But you're missing the 'o' in there to turn ut from newer to newest..

[robbence]

I could see the more literal translation (newest) being used in more modern family structures (adoption, remarriages). Seems like it should be accepted, with a note that the alternative translation is "youngest".

[BillyWonde1]

What about "he is my newer brother"?

[anubina]

Why say novo when you can say jovem? Annoying

[Danmoller]

The expression "meu irmão mais jovem" is weird. It's not wrong, but it's weird.

[kitsune1977]

I really don't know...but we also use "velho": "ele é meu irmão mais velho/novo". And we use it normally...

[pietvo]

Do they really use "novo" instead of "jovem"?

[kitsune1977]

Yes. Always.

[ivano.elia]

I clearly hear the "o" before the meu

[terminalmage]

How do you distinguish between younger and youngest brother?

[Gogogodzilla333]

Wouldn't "He is my younger brother" be:

"Ele é meu irmão mais jovem"?

[iziki010]

"He is my youngest brother" would be more accurate

[frozen3v0lution]

Looking back at this now, it would seem that because "mais" means more and not "most" that "younger" would work better than "youngest"

[Danmoller]

Both are correct.

• Mais novo = younger
• O mais novo = youngest

Now, since you have "o irmão" (defined by "meu"), the distinction gets a little blurry. But "younger" is indeed the best option.

[TKey718]

I thought it was, "He is my much younger brother." Is that possible?

[Danmoller]

"Muito mais novo".

Your sentence has an additional word.