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

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





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

immature or lacking adult sophistication

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image567572573

Which of these is a synonym of unctuous?

prompt angry oily maudlin
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

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

TAKE THE QUIZ