|Sometimes shortened to: decay, Also called: disintegration disintegration of a nucleus that occurs spontaneously or as a result of electron capture. One or more different nuclei are formed and usually particles and gamma rays are emitted|
|an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle.|
|a printed punctuation mark (‽), available only in some typefaces, designed to combine the question mark (?) and the exclamation point (!), indicating a mixture of query and interjection, as after a rhetorical question.|
|radioactive decay (rā'dē-ō-āk'tĭv) Pronunciation Key
The spontaneous transformation of an unstable atomic nucleus into a lighter one, in which radiation is released in the form of alpha particles, beta particles, gamma rays, and other particles. The rate of decay of radioactive substances such as carbon 14 or uranium is measured in terms of their half-life. See also decay, radioisotope.