plas·mid | \ˈplaz-məd \

Definition of plasmid 

: an extrachromosomal ring of DNA especially of bacteria that replicates autonomously

Examples of plasmid in a Sentence

Recent Examples on the Web

The researchers found that S. typhi had gained more resistance genes by acquiring a plasmid, a circular piece of DNA, from another bacterium (a process known as horizontal gene transfer). The Economist, "A strain of typhoid could become virtually untreatable," 26 Apr. 2018 Worse, the antibiotic-resistant DNA can be carried in little cassettes of genetic material called plasmids that bacteria can slip in their entirety to one another and to other species of bacteria. NBC News, ""Nightmare bacteria" are trying to spread in the U.S., CDC says," 3 Apr. 2018 Genetic sequencing revealed that a common, aggressive MDR typhoid strain called H58 interacted with another bacteria, likely E. coli, and acquired from it an additional DNA molecule, called a plasmid, that coded for resistance to ceftriaxone. Emily Baumgaertner, New York Times, "‘We’re Out of Options’: Doctors Battle Drug-Resistant Typhoid Outbreak," 13 Apr. 2018 To obtain appropriate plasmids the foundry’s customers may simply order parts from the library. The Economist, "The gene machineRobotic labs for high-speed genetic research are on the rise," 1 Mar. 2018 The genes comprising a potential circuit are then assembled into circular DNA molecules called plasmids. The Economist, "The gene machineRobotic labs for high-speed genetic research are on the rise," 1 Mar. 2018 The cells are subjected to electrical pulses that briefly open holes in their outer membranes, allowing the plasmids to flow in. Bradley J. Fikes,, "OncoSec Medical to hold stock offering," 31 Jan. 2018 When the plasmid in question contains drug-resistant genes, the gonorrheal bacteria acquiring it become resistant to antibiotics, too. Aneri Pattani, New York Times, "A Dangerous, ‘Silent Reservoir’ for Gonorrhea: The Throat," 31 July 2017 That included plasmids — little cassette-like pieces of genetic material that different species of bacteria can swap. Maggie Fox, NBC News, "Houston Had This Superbug Problem for Years and Never Knew," 16 May 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'plasmid.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of plasmid

1952, in the meaning defined above

History and Etymology for plasmid

plasma + -id entry 2

Keep scrolling for more

Learn More about plasmid

Statistics for plasmid

Look-up Popularity

Time Traveler for plasmid

The first known use of plasmid was in 1952

See more words from the same year

Keep scrolling for more

More Definitions for plasmid


plas·mid | \ˈplaz-məd \

Medical Definition of plasmid 

: an extrachromosomal ring of DNA that replicates autonomously and is found especially in bacteria — compare episome

More from Merriam-Webster on plasmid Encyclopedia article about plasmid

Comments on plasmid

What made you want to look up plasmid? Please tell us where you read or heard it (including the quote, if possible).


a state of commotion or excitement

Get Word of the Day daily email!

Test Your Vocabulary

Words from Greek and Roman Mythology Quiz

  • the-triumph-of-venus-by-alessandro-magnasco
  • Boreal comes from the name of the ancient Greek god of which wind?
True or False

Test your knowledge - and maybe learn something along the way.

Dictionary Devil

Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!