words of one syllable, in
In simple terms, as in I don't understand financial derivatives—can you explain them in words of one syllable? [Colloquial; 1920s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.