I wish that. For example, If only I had known you were coming I would have met your plane, or If only it would snow on Christmas Eve. [c. a.d. 1000] For a synonym, see would that.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.