One that detects, especially a mechanical, electrical, or chemical device that automatically identifies and records or registers a stimulus, such as an environmental change in pressure or temperature, an electric signal, or radiation from a radioactive material.
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.