前缀actino-在元音前变成actin-,意思是“A ray or beam 光线，束”。前缀actino-来源极其复杂和曲折，它来源于希腊语aktis,意思是“ray, radiance 光线，射线等多个意思”，aktis可能与梵文aktuh (意思是“light,ray”)同族。
before vowels actin-, word-forming element meaning "pertaining to rays," from Greek aktis (genitive aktinos) "ray, radiance;" perhaps cognate with Sanskrit aktuh "light, ray," Gothic uhtwo "dawn, daybreak," Lithuanian anksti "early."
Some examples refer to rays of light. Radiation that is able to cause chemical reactions, as light does on photographic film, is said to be actinic; an actinometer is an instrument for measuring the intensity of radiation.Actinium is a rare radioactive element (atomic number 89), so named because it glows in the dark; hence actinide, a member of the series of radioactive elements, including uranium and plutonium, of which actinium is the first.
Other examples refer to structures that radiate from a centre. Something actinomorphic, such as a starfish or the flower of a daisy, has radial symmetry. An actinomycete (Greek mukēs, mukēt-, fungus) is a bacterium with a filamentous form, which was formerly considered to be a fungus, the ray-fungus; these can cause disease in humans and animals; actinomycin is a member of a group of antibiotics extracted from soil bacteria of this genus.