Date more than one person; avoid an exclusive commitment. For example, All of Joe's friends are married now, but he continues to play the field. This term originated in British horseracing, where it meant “to bet on every horse in a race except the favorite.” It was transferred to other activities about 1930.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.