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: RNA or a segment of RNA that is composed of a polynucleotide chain consisting entirely of adenylic acid residues and that codes for polylysine when functioning as messenger RNA in protein synthesis

Word History

Etymology

poly- + adenylic acid

First Known Use

1957, in the meaning defined above

Time Traveler
The first known use of poly(A) was in 1957

Browse Nearby Words

Cite this Entry

“Poly(A).” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/poly%28A%29. Accessed 29 Nov. 2025.

Medical Definition

poly(A)

noun
: RNA or a segment of RNA that is composed of a polynucleotide chain consisting entirely of adenine-containing nucleotides and that codes for polylysine when functioning as messenger RNA in protein synthesis

called also polyadenylate, polyadenylic acid

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