downer

Etymology 1

down + -er

noun

1. (slang) A negative drug trip.
   Normally those pills give me a boost, but last night they gave me a downer.
2. (slang) A drug that has depressant qualities.
3. (slang) Something or someone disagreeable, dispiriting or depressing; a killjoy.
   You don't really need to know me. I'm kind of a downer. 2009, Spike Jonze, Where the Wild Things Are
   Geffen had never understood why such a downer of a film was being released over the holidays. 2010, Nicole LaPorte, The Men Who Would Be King
4. A livestock animal that has collapsed.
   The ten-dollar bill was for eating money and the prod pole to be used when the train stopped for water in getting "downers" back on their feet. 1964, John Hendrix, If I Can Do It Horseback: A Cow-Country Sketchbook, page 40
   In 1993, Farm Sanctuary produced undercover footage of downers being lifted by forklift at Hallmark, prompting introduction of a California downer cattle law the next year. Either management provided instructions to get the downers moving or was asleep at the wheel and let employees run wild — in either case, it's an indictment of management. 2009, United States. Congress. Senate. Committee on Appropriations. Subcommittee on Agriculture, Rural Development, Food and Drug Administration, and Related Agencies, Hallmark/Westland Meat Recall
   The two plants where I saw great reductions in downers have reduced, but not eliminated Paylean use. 2009, Meat & Poultry - Volume 55, Issues 7-12, page lxxii
5. A form of industrial action in which workers down tools and refuse to work.
   In the Workplace Industrial Relations Survey, a strike may be a downer or a stoppage as defined by the Department. 1978, C. T. B. Smith, Great Britain. Dept. of Employment, Manpower Papers (issue 15, page 158)
   Cowley experienced a rash of 'downers' — short, sharp, unofficial strikes. 1985, Alex Callinicos, Mike Simons, The Great Strike: The Miners' Strike of 1984-5 and Its Lessons

Etymology 2

Perhaps related to tanner (“sixpence”).

noun

1. (UK, slang, obsolete) A sixpence.
   The price of a case (five shillings piece bad) from the smasher is about one shilling; an alderman (two and sixpence) about sixpence; a peg (shilling) about threepence; a downer or sprat (sixpence) about twopence. 1859, Snowden's magistrates assistant, page 90