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actinic rays electromagnetic radiation, such as x-rays or ultraviolet light, that can produce an image on a photographic emulsion.
actinide any of the chemical elements of the actinide series.
actinide series the series of chemical elements, mostly synthetic and all radioactive, that have from eighty-nine to 103 protons per atom.
actinism the property of radiation that produces chemical activity.
actinium a radioactive chemical element of the rare-earth group that has eighty-nine protons in each nucleus. (symbol: Ac)
actinogen any of the radioactive chemical elements.
actinoid having a radial or star-shaped form, as certain sea creatures.
actinomycin any of several antibiotics derived from soil bacteria that work against certain other bacteria and fungi.
actinomycosis an infectious disease of animals and humans that is caused by parasites and produces abscesses, esp. in the jaws.
actinozoan see anthozoan.
action something that is done, is being done, or will be done. [8 definitions]
actionable providing legitimate grounds for legal action.
action-adventure a genre of films, video games, and the like having an exciting undertaking involving risk and danger as its main story line, and involving one or more heroes engaged in a series of physical challenges. [2 definitions]
actionless combined form of action.
action movie a film whose story line focuses on conflict and fast-paced activity, esp. involving physical violence, feats of strength and agility, and chase scenes.
action-packed of a film, video, story, or the like, filled with scenes depicting action, danger, and exciting events.
action verb a verb that shows its subject performing some action. "Run," "eat," "fly," and "sing" are examples of action verbs.
activate to initiate action in; make active. [5 definitions]
activated carbon a form of very porous and thus very absorbent carbon, produced by heating charcoal so as to empty out contained gases, and used to absorb other gases, recover solvents, deodorize, and the like; activated charcoal.
activated charcoal see activated carbon.
active constantly doing something; busy; energetic. [6 definitions]