word - Don't clear your terminal history

You woke up this morning locked in a room. The only apparent exit is a door with a terminal. On the screen you see the following:

> einn
Access granted. Door opened.
> três
Access granted. Door opened.
> dhá
Access granted. Door opened.
> seis
Access granted. Door opened.
> seven

Access granted. Door opened.
> cinq
Access granted. Door opened.
> vier
Access granted. Door opened.
> 

The last line seems to be waiting for some input from you...

Answer

The answer is

twaalf, the Dutch word for the number twelve

The languages

go from West to East: Iceland $\rightarrow$ Portugal $\rightarrow$ Ireland $\rightarrow$ Spain $\rightarrow$ UK $\rightarrow$ France $\rightarrow$ Belgium.
Hence the next language should be Dutch.

The numerical values

follow the 4-bit Gray code (see here): 0000=0, 0001=1, 0011=3, 0010=2, 0110=6, 0111=7, 0101=5, 0100=4, 1100=12, 1101=13, 1111=15, 1110=14, 1010=10, 1011=11, 1001=9, 1000=8.
Hence the next number should be 12.