- Of or relating to elementary particles with energies exceeding hundreds of thousands of electron volts. (adjective)
- Yielding a large amount of energy upon undergoing chemical reaction. (adjective)
- Vigorous; dynamic. (adjective)
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.