other day, the
One day recently, a short time ago, as in I saw her in the museum the other day. This term originally meant either “the next day” or “the preceding day” (tomorrow or yesterday). In its current meaning it was first recorded in 1421.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.