Verb
put a damper on (third-person singular simple present puts a damper on, present participle putting a damper on, simple past and past participle put a damper on)
(idiomatic) To stop people from enjoying an activity.
Synonyms: rain on somebody's parade, upset the applecart; see also Thesaurus:put a damper on
John told us he had lost his job, which put a damper on the celebrations.