Solution 1:

Commode: (from The American Heritage® Dictionary)

  • A low cabinet or chest of drawers, often elaborately decorated and usually standing on legs or short feet.

  • A movable stand or cupboard containing a washbowl.

  • A toilet.

Toilet vs commode:

  • Why do some folks call the toilet a commode? At one point in history, the commode was a piece of furniture you’d put a chamberpot in. Today, commode is still a common term heard in the American South. Elsewhere, the term commode denotes a kind of cabinet, causing confusion when journalists mistook reports of Congressman Randy “Duke” Cunningham taking a bribe in the form of a pair of antique commodes worth more than $7000. What do you call your porcelain throne?

Ngram - Toilet vs commode

Why the Toilet is sometimes called a “John ”?

  • The term is thought to derive from Sir John Harrington or, at the least, to have been popularized due to Harrington. (There are a few references of the toilet being called “Cousin John”, as well as many references to it being called “Jake” and other such generic names, before Harrington was born; but it is generally agreed that why we now call it “John” is because of Harrington and not from the old “Cousin John”).

Toilet is the term you should use, commode has a restricted use though it is still common in some parts of US. John as well as other nouns are slang terms and should be used with care. (See extract about "John" ).

Solution 2:

"Toilet" is the "official" US term for the thing upon which you sit, though occasionally "stool" is used.

See, for example, this page selling toilets: http://www.homedepot.com/b/Bath-Toilets-Toilet-Seats-Bidets/N-5yc1vZbzae

There are of course multiple slang terms -- John, throne, crapper, can,pot, etc.

"Commode" is sometimes used but it is also the name for a piece of bedroom furniture (one that was sometimes used to hold a bedpan or chamber pot, hence the connection), and one might therefore interpret the term as referring to furniture.

Solution 3:

As several answers have noted in passing, Americans generally do not use toilet to refer to the room, unlike the French (and apparently others). For that they use rest room, Men's room, Women's room, bath room (typically at home, not public), or (old-fashioned, and for the Women's room only) powder room.

When Americans use the word toilet they mean what you sit on: the toilet bowl together with the toilet seat mounted on top of it.

In the US, the expression go to the __ room typically means to go to that room, but it sometimes is used as a euphemism for using the toilet. The expression go to toilet unambiguously means using it.