water closet：A lavatory flushed by water 抽水马桶
Public restrooms around the world use the abbreviation "W.C., " meaning "water closet."
如，On the first floor (the galley) there are baths, swimming pool and water closet.
其实上面的英文解释里面已经有了两个了，restroom是最常见的。另外一个不太常见的是lavatory，这个单词在商场等也很难见到，飞机上的厕所是用这个词儿。从有道词典上查到的解释是：A lavatory is a toilet or a room with a toilet in it. 其实它用于只有toilet而没有洗澡设施的简易厕所，火车上的洗手间也是这个词儿，其他地方少见。
A toilet is a large bowl with a seat, or a platform with a hole, which is connected to a water system and which you use when you want to get rid of urine or faeces from yourbody. 抽水马桶
A toilet is a room in a house or public building that contains a toilet. 厕所，如mobile toliet, portable toilet 是指移动厕所
You can say that someone goes to the toilet to mean that they get rid of waste substances from their body, especially when you want to avoid using words that you think mayoffend people.
其实个人觉得最常见的还是下面几个：washroom, restroom, bathroom, lady's room (man's room ), Women's, lady's, or ladies.
washroom：A washroom is a room with toilets and washing facilities, situated in a large building such as a factory or an office.
Sorry, I had to go to the washroom.
restroom：In a restaurant, theatre, or other public place, a restroom is a room with a toilet for customers to use.
There are following facilities on the beach: a shower, a restroom, and a changing room.
Can I borrow your restroom?
bathroom: A bathroom is a room in a house or public building that contains a sink and toilet.People say that they are going to the bathroom when they want to say that they aregoing to use the toilet. You can say that someone goes to the bathroom to mean that they get rid of waste substances from their body, especially when you want to avoid usingwords that you think may offend people.
Where is the nearest bathroom?
Watch the color of your urine when you go to the bathroom.
man's room and lady's room; or Women's, lady's, ladies.
Excuse me, do you know where the man's room is?
当然啦，你也可以说：Where can I wash my hands? or Where is John ? 这就比较酸了，哈哈。