Questions & Answers about Jeg gemmer nøglen i min lomme.
Because nøglen is the definite form: the key.
In Danish, many nouns add a suffix for definiteness:
- en nøgle = a key
- nøglen = the key
So Jeg gemmer nøglen i min lomme uses the key, not a key.
The -n is the definite ending for a common-gender noun.
For this noun:
- en nøgle = a key
- nøglen = the key
This is very common in Danish. Instead of putting a separate word before the noun, Danish often attaches definiteness to the end of the noun.