upstream

adverb or adjective

up·​stream ˈəp-ˈstrēm How to pronounce upstream (audio)
1
: in the direction opposite to the flow of a stream
2
: in or to a position within the production stream closer to manufacturing processes
make most of its money upstream, selling cheap crude … to refineriesJohn Quirt
3
biochemistry : toward the beginning of a series of cellular processes : preceding a linked molecular event occurring in a sequence
Many signaling pathways possess intrinsic negative feedback by which a downstream event in a pathway turns off an upstream event.Harvey Lodish et al.

Examples of upstream in a Sentence

Recent Examples on the Web
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In 1982, while most game developers were busy with space invaders and maze ghosts, Bill Williams created something far more profound: a game about swimming upstream against impossible odds. ArsTechnica, 1 Apr. 2025 Historically, these fish have matured to adulthood in the Pacific Ocean, then returned upstream to cold, fresh water in the mountains each spring. Sarah Kuta, Smithsonian Magazine, 28 Feb. 2025 The cost of fixing defects skyrockets later in the lifecycle, so move testing upstream. Maneesh Sharma, Forbes, 27 Feb. 2025 While krill generally swim straight upstream in what’s known as rheotaxis, the presence of penguin guano appeared to immediately influence their behavior. Andrew Paul, Popular Science, 20 Mar. 2025 See All Example Sentences for upstream

Word History

First Known Use

1681, in the meaning defined at sense 1

Time Traveler
The first known use of upstream was in 1681

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Cite this Entry

“Upstream.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/upstream. Accessed 8 Apr. 2025.

Kids Definition

upstream

adverb or adjective
up·​stream ˈəp-ˈstrēm How to pronounce upstream (audio)
: at or toward the beginning of a stream : against the current
salmon swimming upstream

Medical Definition

upstream

adverb or adjective
up·​stream ˈəp-ˈstrēm How to pronounce upstream (audio)
1
: in a direction along a molecule of DNA or RNA opposite to that in which transcription and translation take place and toward the end having a phosphate group attached to the position labeled 5′ in the terminal nucleotide
… stretches of DNA upstream of genes—are known as promoters.Matt Ridley, Time
compare downstream sense 1
2
: toward the beginning of series of cellular processes : preceding a linked molecular event occurring in a sequence
It's equally important to focus on additional mechanisms that are upstream of amyloid formation and mechanisms downstream that are involved in the actual degenerative processes within neurons.Marc Tessier-Lavigne, quoted in Science

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