2. Proceeding or occurring in intervals of 20.
3. Based on or relating to 20.
[From Latin vīgēsimus, variant of vīcēsimus, twentieth, from vīgintī, twenty; see wīktī- in the Appendix of Indo-European roots.]
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.