This has been bothering me, ever since I started learning English. It is concerning " 's " ; Which one is correct for the following examples ?

Car steering wheel or car's steering wheel

Door knob or door's knob

Computer screen or computer's screen

Dog house or dog's house,

Cell membrane (used in textbook) or cell's membrane

Road surface (used in textbook) or road's surface

Berlin streets or Berlin's streets

There are thousands of others, so I am looking for an "official rule".
Thank you


The generative form (with the 's) is used to describe the relationship of the object to another object (usually ownership). The attributive form describes an attribute of the object itself. In many cases the distinction is subtle and the forms can be used interchangeably.

Consider the example of the dog house: A structure designed for use by a dog is a dog house even if there is no dog to live in it. The word dog describes an attribute of the house itself. If there is a dog living in the house then it is also a dog's house because it is owned by a dog.

Likewise a screen of the type that works with a computer is a computer screen regardless of whether or not there is a computer to go with it. If you want to describe it in relation to the computer, it is the computer's screen.

Berlin streets describe some attribute of the streets (eg. "Berlin streets are often crowded.") while Berlin's streets describes the streets relationship to the city. In many, but not all, cases these could be used interchangeable. You could say "Berlin's streets are often crowded." but you need to use the genitive form to say "Berlin's streets are maintained by its city council."

  • +1 , nice examples ; but I think , we should also consider the cases where the first noun is used as an adjective, eg "computer" is an adjective in "computer screen"
    – Prem
    Oct 10 '17 at 9:49
  • 1
    @Prem Yes they are all adjectives but some are genitive and others are attributive.
    – smatterer
    Oct 10 '17 at 12:52

Hmm, in these instances you have provided, it seems that the first of the two options comes correct in all of them except "Berlin's streets".

Car steering wheel, door knob, computer screen, dog house, cell membrane, and road surface: these are all compound nouns that have already been accepted into common use, so there isn't really a need to indicate possession.

Berlin's sreets: this one is an exception, because Berlin, being a place, is a proper noun. Just as you would indicate possession for a person, eg: "John's laptop", you would indicate possession in "Berlin's streets". Besides, I doubt "Berlin streets" has been accepted in popular use...

  • 1
    London streets are crooked add narrow. So are Berlin streets. Another example: Massachusetts voters usually vote for the Democratic candidate. Oct 10 '17 at 11:31

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