Etymology
Advertisement

radioactive (adj.)

1898, of an atomic nucleus, "capable of spontaneous nuclear decay releasing ionizing emissions," from French radio-actif, coined by Pierre and Marie Curie from radio-, combining form of Latin radius "ray" (see radius) + actif "active" (see active). Of processes, etc., "involving or produced by radioactivity," by 1903.

Entries linking to radioactive

radius (n.)

1590s, "cross-shaft, straight rod or bar," from Latin radius "staff, stake, rod; spoke of a wheel; ray of light, beam of light; radius of a circle," a word of unknown origin. Perhaps related to radix "root," but de Vaan finds that "unlikely." The classical plural is radii. 

The geometric sense of "straight line drawn from the center of a circle to the circumference" is recorded from 1650s. Meaning "circular area of defined distance around some place" is attested from 1853. As the name of the shorter of the two bones of the forearm from 1610s in English (the Latin word had been used thus by the Romans).

active (adj.)
mid-14c., "given to worldly activity" (opposed to contemplative or monastic), from Old French actif (12c.) and directly from Latin activus, from actus "a doing" (from PIE root *ag- "to drive, draw out or forth, move").

As "capable of acting" (opposed to passive), from late 14c. Meaning "energetic, lively" is from 1590s; that of "working, effective, in operation" (opposed to inactive) is from 1640s. Active voice is recorded from 1765; grammatical use of active, signifying performance and not endurance of an action, dates from mid-15c. (opposed to passive or reflexive).
Advertisement
Advertisement
Definitions of radioactive

radioactive (adj.)
exhibiting or caused by radioactivity;
radioactive decay
radioactive isotope
radioactive fallout
From wordnet.princeton.edu

Dictionary entries near radioactive

radicate

radicle

radicular

radio

radio-

radioactive

radioactivity

radio-carbon

radiocast

radiography

radioisotope

© 2001-2022 Douglas Harper