buzzkill

From buzz +‎ kill. See buzz (“feeling of energy or excitement”).

• (General American) IPA^(key): /ˈbʌzkɪl/

• Audio (General Australian):

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buzzkill (plural buzzkills)

1. (slang) Something that—or someone who—spoils an otherwise enjoyable event.
2. (slang) A person who attends a social event and occupies his or her time with unsociable activities.

• (something or someone who spoils an enjoyable event): dampener, killjoy, wet blanket, (person), party-pooper (person); see also Thesaurus:spoilsport