touch on

touch on idiom
    Also, touch upon.
  1. Mention briefly or casually in passing, as in He barely touched on the subject of immigration. [First half of 1600s]
  2. Approach closely, verge on, as in This frenzy touched on clinical insanity. [Early 1800s]

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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