It is one word, the compound word "bathroom." This American euphemism for a 'lavatory' has been confusing British travelers ever since it's 1780 adoption into the lexicon.
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Both. Bath=room= bathroom bath and room are two different words it is a compound word
Two words. It is a room of the press.
It can be either, depending on context. Birdbath, as an object, is one word, a bird taking a bath would be two words
'Fitting room' is two words.
No it is two words: post room.
two words, locker room
Bathroom is one word. An example sentence would be "the bathroom is painted turquoise.
Dictionary dot com lists both breakroom and break room as options for this word. However, in the example given of the word being used in a sentence they display "breakroom".
Ballroom is one word meaning a large room used for dancing.
As in "the layout of the room is very nice", it is one word. As in "I will lay out all the pens on the table", it is two words.
Food service is two words. An example sentence is "the food service is good here".
Mail room is debatable. It is becoming more and more acceptable to use it as one word. If you type in mailroom into a sentence and ask for spell check you will get a misspell.