Household and car keys are kept on a keyring to keep them together. Some people have key hooks at home to hang keys.
Other types of key such as those on a musical instrument or computer are held together on a keyboard
They are called book-ends.
Yes, a "dam" is a barrier that holds back water, a real thing.
When you say one thing is another, it is called a metaphor.
A detested person is called a pariah, a detested person, idea, or thing is called an anathema.
The plural is keys.
The thing that is a sash like object that holds a katana is called an obi.
a clamp
The thing that holds dead man ashes is called an Urn I believe :)
A sheath.
Filament.
A bobbin or a Spool
Tomb or sarcophagus
sunglasses holder?
an easel
The "necklace" piece is called a Lanyard. Then the other piece that holds the card is called an ID Protector.
Always called it a tree stand.
Hopper or Loader