Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

actin

play
noun ac·tin \ˈak-tən\

Definition of actin

  1. :  a cellular protein found especially in microfilaments (as those comprising myofibrils) and active in muscular contraction, cellular movement, and maintenance of cell shape



Origin of actin

International Scientific Vocabulary, from Latin actus


First Known Use: 1942


actin-

combining form ac·tin

Definition of actin-

  1. 1 :  having a radiate form <actinolite>

  2. 2 :  actinic radiation (as X rays) <actinometer>



Variants of actin-

or actini- or actino-

Origin of actin-

New Latin, ray, from Greek aktin-, aktino-, from aktin-, aktis; perhaps akin to Old English ūhte morning twilight, Latin noct-, nox night — more at night


Medical Dictionary

actin

play
noun ac·tin \ˈak-tən\

Medical Definition of actin

  1. :  a protein found especially in microfilaments (as those comprising myofibrils) and active in muscular contraction, cellular movement, and maintenance of cell shape—see f-actin, g-actin




actin-

combining form ac·tin

Medical Definition of actin-

  1. 1:  of, utilizing, or caused by actinic radiation (as X-rays) <actinotherapy>

  2. 2:  actinomycete <actinophage>



Variants of actin-

or actini- or actino-

Learn More about actin


Seen and Heard

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

WORD OF THE DAY

February 11, 2016

the holder of an office

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image33683556

How much does a batman (the Turkish unit of measurement) weigh?

100 pounds 196.5 pounds 2.2 pounds 16.96 pounds
Name That Thing

10 quick questions: hear them, spell them, and see how your skills compare to the crowd.

TAKE THE QUIZ
SCRABBLE® Sprint

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

TAKE THE QUIZ