down ‧ er /ˈdaʊnə $ -ər/ BrE AmE noun informal
1 . [countable] a drug that makes you feel very relaxed or sleepy ⇨ upper
2 . [singular] a person or situation that stops you feeling happy:
The weather was a bit of a downer.
3 . be on a downer British English to be sad or experiencing a series of sad events:
What’s up with Ruth? She’s been on a downer all week.