| actinoid | (n) any of a series of radioactive elements with atomic numbers 89 through 103, Syn. actinon, actinide |
| actinoid | (adj) having a radial form, Example: starfish are actinoid--that is, they are radially symmetrical |
| actinolite | (n) a green mineral of the amphibole group; calcium magnesium iron silicate |
| actinomeris | (n) used in some classification systems for plants now included in genus Verbesina, Syn. genus Actinomeris |
| actinometer | (n) an instrument for measuring the intensity of electromagnetic radiation (usually by the photochemical effect) |
| actinometric | (adj) of or related to actinometry, Syn. actinometrical |
| actinometry | (n) measuring the intensity of electromagnetic radiation (especially of the sun's rays) |
| actinomorphic | (adj) capable of division into symmetrical halves by any longitudinal plane passing through the axis, Syn. actinomorphous, Ant. zygomorphic |
| actinomyces | (n) soil-inhabiting saprophytes and disease-producing plant and animal parasites |
| actinomycetaceae | (n) filamentous anaerobic bacteria, Syn. family Actinomycetaceae |
| Actino-chemistry | n. Chemistry in its relations to actinism. Draper. [ 1913 Webster ] |
| Actinogram | n. [ Gr. &unr_;, &unr_;, ray + -gram. ] A record made by the actinograph. |
| Actinograph | n. [ Gr. &unr_;, &unr_;, ray + -graph. ] An instrument for measuring and recording the variations in the actinic or chemical force of rays of light. Nichol. [ 1913 Webster ] |
| Actinoid | a. [ Gr. &unr_;, &unr_;, ray + -oid. ] Having the form of rays; radiated, as an actinia. [ 1913 Webster ] |
| Actinolite | n. [ Gr. &unr_;, &unr_;, ray + -lite. ] (Min.) A bright green variety of amphibole occurring usually in fibrous or columnar masses. [ 1913 Webster ] |
| Actinolitic | a. (Min.) Of the nature of, or containing, actinolite. [ 1913 Webster ] |
| Actinology | n. [ Gr. &unr_;, &unr_;, ray + -logy. ] The science which treats of rays of light, especially of the actinic or chemical rays. [ 1913 Webster ] |
| Actinomere | n. [ Gr. &unr_;, &unr_;, ray + &unr_; part. ] (Zool.) One of the radial segments composing the body of one of the Cœlenterata. [ 1913 Webster ] |
| Actinometer | n. [ Gr. &unr_;, &unr_;, ray + -meter ] |
| Actinometric | a. Pertaining to the measurement of the intensity of the solar rays, either |