There are three other French words that would be used for "tub" before "baignoire". I think "baignoire" can be a "tub", but a "tub" is not necessarily a "baignoire". http://dictionnaire.reverso.net/francais-anglais/baignoire
One of Duolingo's translations for "baignoire" is "conning tower". I typed "he is in the conning tower", and was told it was wrong. Clearly, that's not what the expected answer was supposed to be, so maybe the offered definitions shouldn't include translations that make no sense in the given context....
While I agree that it's frustrating, you can also look at it from the point of view that it's forcing you to think more as you translate. You can't just blindly transcribe words based on the provided definitions. I think the additional difficulty can be extremely valuable. :D
Absent any context, "he is in the conning tower" and "he is in the bathtub" are both perfectly valid translations, so there's no extra "thinking" involved. Baignoire is indeed a French word for the conning tower of a submarine.
The problem is that Duolingo sees it as an incorrect answer, even though it is correct, and Duo itself is offering the translation, "conning tower".
but this sentence is in the Household category which makes bath tub a much better translation than conning tower would be, unless one's household is a submarine of course.
We do not use "tub" or "bathtub" in UK, although we know these are commonly used words in USA. We say "bath," or perhaps bathroom.
Yes "Il est dans la baignoire" can be translated as "He is in the bath" but not "bathroom" which would be "salle de bain"
Yes, I didn't make myself entirely clear. Sorry. I was refering to the phrases most commonly used for bathroom activities in England, where we do not tend to be quite so specific about which bathroom fitments are actually being used, especially when it is somebody else using them. "Bathroom," therefore, was not intended to translate from any specific French terminology, but more to contrast with the American precision of "bathtub." Also, in UK tubs are things more for growing plants in.