This is the 12800th most frequent Polish word.
nimo
The word "nimo" is not a standard Polish word. It may be a typo or a dialectal term.
The word 'niemożliwe' is used here as an adjective meaning 'impossible'.
Niemożliwe, aby on przyszedł dzisiaj.
It is impossible for him to come today.
The word 'nimo to' is used as a phrase meaning 'nevertheless', showing concession.
Chociaż był zmęczony, nimo to poszedł na spacer.
Although he was tired, nevertheless, he went for a walk.
Here 'nimo' is used in the sense of 'in spite of', indicating opposition to an expected result.