1. Any of various chiefly Mediterranean weeds or ornamentals of the genus Alyssum in the mustard family, having racemes of white or yellow flowers. Also called madwort.
2. Any of various similar plants in the mustard family, especially sweet alyssum.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.