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a combining form with the meaning “ray, beam,” used in the formation of compound words, with the particular senses “radiation” in the physical sciences (actinometer) and “having raylike structures,” “radiate in form” in biology (actinomyces; actinopod).
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Also especially before a vowel, actin-.
Origin of actino-
<Greek, combining form representing aktī́s (genitive aktînos) ray, beam; see -o-
Words nearby actino-
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022
British Dictionary definitions for actino-
before a vowel actin-
indicating a radial structureactinomorphic
indicating radioactivity or radiationactinometer
Word Origin for actino-
from Greek aktino-, from aktis beam, ray
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012