to become popular or fashionable
to grasp mentally; understand
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Other Idioms and Phrases with catch on
Understand, as in Aunt Mary doesn't catch on to any jokes. The verb to catch alone was used with this meaning from Shakespeare's time, on being added in the late 1800s. Also see get it, def. 2.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.