1
a
: a common Eurasian venomous snake (Vipera berus) that attains a length of about two feet (0.6 meter), varies in color from red, brown, or gray with dark markings to black, and is usually not fatal to humans
broadly
: any of a family (Viperidae) of venomous snakes that includes Old World snakes (subfamily Viperinae) and the pit vipers
b
: a venomous or reputedly venomous snake
2
: a vicious or treacherous person
Examples of viper in a Sentence
a viper sliding silently through the field
Recent Examples on the Web
One of the vipers is Mirren’s Maeve, Conrad’s wife.
—
Anne Thompson, IndieWire, 5 June 2025
Amidst the many water monitors and garden lizards, guests might catch a glimpse of a snake lounging along the preserve, with resident species spanning from the Russell’s viper to the king cobra, a colossal creature that’s capable of measuring in at more than five meters in length.
—Jared Ranahan, Forbes.com, 28 June 2025
This finding extends the geographic range of the Persian horned viper.
—Real-Time News Team, Miami Herald, 20 June 2025
Snakes are all over the desert, hiding in plain sight, especially in Joshua Tree National Park, where people regularly hike and hang out without noticing any vipers.
—Zoey Lyttle, People.com, 19 June 2025
See All Example Sentences for viper
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Anne Thompson, IndieWire, 5 June 2025
Amidst the many water monitors and garden lizards, guests might catch a glimpse of a snake lounging along the preserve, with resident species spanning from the Russell’s viper to the king cobra, a colossal creature that’s capable of measuring in at more than five meters in length.
—Jared Ranahan, Forbes.com, 28 June 2025
This finding extends the geographic range of the Persian horned viper.
—Real-Time News Team, Miami Herald, 20 June 2025
Snakes are all over the desert, hiding in plain sight, especially in Joshua Tree National Park, where people regularly hike and hang out without noticing any vipers.
—Zoey Lyttle, People.com, 19 June 2025
See All Example Sentences for viper
Cite this Entry
“Viper.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/viper. Accessed 22 Jul. 2025.
Copy CitationKids Definition
viper
noun
vi·per
ˈvī-pər 
1
: any of a family of poisonous snakes having heavy bodies, broad heads, and hollow tube-shaped fangs and including Old World snakes and the pit vipers
2
: any snake that is poisonous or that is believed to be poisonous
Medical Definition
viper
noun
vi·per
ˈvī-pər
1
: a common Eurasian venomous snake of the genus Vipera (V. berus) that attains a length of about two feet (0.6 meter), varies in color from red, brown, or gray with dark markings to black, and whose bite is usually not fatal to humans
broadly
: any snake of an Old World subfamily (Viperinae) of the family Viperidae
2
3
: a venomous or reputedly venomous snake
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