In English as in many language, there are things which their names are made of two words or nouns, such as: shower-stall, toilet-room, washing-machines, and so on. My question is what is the name of the first component and the second component? (As far as I know the second component only can become plural)
Things which their names are made of two words are called: compound words.
Then there are "open compound words" and "closed compound words" as follow:
open compound words, such as living-room, coffee-mug.
closed compound words, such as bookstore, notebook.
Source: compound words.