Hi Arkadiusz, I think this is a mistake. Maybe you HEARD this, rather than reading it? I think the phrase should be "to put a DOWNER" on something. This means to give it a negative vibe. For example, "When I failed my exam on Friday, it really put a downer on my weekend." OK? Hope this helps :-)

‘Dour’ is a somewhat old-fashioned but common word, but it makes no sense in this context. Jon’s answer may be the best. Thinking about your question made me learn that ‘put a downer on something’ is an idiom. It’s not one that I personally would use or have heard. I would say that ‘something is a downer’ or ‘something caused something to be a downer’. It’s fascinating to me how English evolves.

I would call it a mistake because the adjective "dour" is used as a noun. It would be like saying "it puts a sad on my workout". The proper way to turn "dour" into a noun would be to say "dourness".

"Dour" means intentionally sad, grumpy, or negative. For example: "His dour mood made the birthday party less fun than we expected". "Dour" definitely would not work in your example sentence. As others mentioned, you might be hearing the word "damper" or "downer".

I have never heard the word Dour before in my life. I would guess the other people here are Googling it too. I think Jon is probably right - Downer is probably the word that was said, although I don't know how you could miss the N sound in that word.