Definition of "tester" []

• One that tests: a battery tester; a taste tester. (noun)
• A canopy, as over a bed or pulpit. (noun)
• See teston. (noun)

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.

• "This tester is a small 3 prong unit with 2 yellow lights and 1 red light, made by A.W. Sperry."
• "… the word tester refers to the canopy, or roof, that shelters the bed and the alcove."
• "Now, you've shown where MacNeill points out that the generator for biological evolution isn't random (or even random with regard to fitness), and the tester is not limited to natural selection."