actino-

1. 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 ).

actino-

combining_form

1. indicating a radial structure

   actinomorphic

2. indicating radioactivity or radiation

   actinometer

Word History and Origins

Origin of actino-¹

< Greek, combining form representing aktī́s (genitive aktînos ) ray, beam; -o-

Word History and Origins

Origin of actino-¹

from Greek aktino-, from aktis beam, ray